The Prophet (Pbuh) revealed his Prophethood at the age of 40 year as instructed by Allah (swt).
Musa Alahi salam traveled 40 years in the desert.
Musa spent 40 days on Mount Sinai where he received the 10 commandments.
Prophet Ibrahim spent 40 days in a fire and lived because Allah made the fire like flowers.
Prophet Yunus was in a whales mouth for 40 days.
On the 40th ayat of surah baqarah Allah changes the topic.
Forty was the number of days that Prophet Ilyas spent in the wilderness before God appeared to him in a cave on Mount Horeb.
Forty was the number of days that Prophet Isa was tempted in the desert by Satan.
Muhammad (PBUH) was praying and fasting in the cave for 40 days.
Muhammad (PBUH) then had 40 followers to spread the religion of Islam.
Prophets Dauud and Suleiman each ruled for forty years.
Regarding the flood that Noah encountered, it is said that for forty days water continued to pour from the heavens and to stream out over the earth.
Prophet Isa walked the desert and fasted in the wilderness for forty days.
There is also a hadith from Prophet Mohammad (PBUH) that the prayers of a person who gossips would not be accepted for forty days and nights. (Al-Kafi, Vol. 6, p. 400)
Imam Ali has narrated from Prophet Mohammad (PBUH) that one who memorizes and preserves forty hadith relating to their religious needs shall be raised by Allah as a learned scholar on the Day of Resurrection.
It is said that a person’s intellect attains maturity in forty years, everyone according to his own capacity.
It is believed that one who assists a blind man for forty steps becomes worthy of entering heaven.
Imam Baghir has said: “The prayers of someone who drinks wine are not accepted for forty days.”
Believers have also been encouraged to devote themselves to God Almighty for forty days to see the springs of wisdom break forth from their hearts and flow from their tongues.
So what is ur views about significance of 40 in Islam?
Jazak Allah for the quotes but you need to review some of the information. may be a better source would do. For instance,
"Prophet Yunus was in a whales mouth for 40 days."
This is not true. Prophet yunus (jonah)(as) was in the belly of the fish for three days or three days and three nights
mathew 12:40) **For as Jonah was three days and three nights in the belly of a huge fish, so the Son of Man will be three days and three nights in the heart of the earth.**
May Almighty Allah bless u. Ameen. That was the actual point of opening this thread. I need someone who review with me all points mentioned in post# 1 to see whether the info is correct or incorrect. :)
I have heard that Sayyiduna Yunus (AS) was in the belly for 3 days, 7 days and 40 days each from various places ... 7 and 40 days are based on Islamic references.
What I have read is that hazrat yunus (as) left ninevah giving warning that after 40 days, Allah's 'azab' will come over them. In his absence, people of ninevah realized their blunder and did taubah so the imminent 'azab' was averted.
May Almighty Allah bless u. Ameen. That was the actual point of opening this thread. I need someone who review with me all points mentioned in post# 1 to see whether the info is correct or incorrect. :)
I must say that you are true gentleman. you are more than welcome. I will try to review other points as well
I meant that all three are from Islamic sources, but the 7 day idea has become popular amongst the Shi’a and the 40 day idea has become popular amongst the Sunnis. But even the 3 days is a valid opinion not other than it fits with the New Testament.
Here:
They differed as to how long he spent in the belly of the fish. Some said three days; this was the view of Qatadah. Some said seven days; this was the view of Jafar As-Sadiq, may Allah be pleased with him. Some said forty days; this was the view of Abu Malik. Mujahid said, narrating from Ash-Shabi, "It swallowed him in the morning and cast him forth in the evening.‘’ And Allah knows best how long exactly was.
Psyah bhai for explanation. Let me write same points in different way. I think this is how we can test our level of knowledge and in case we are wrong than I hope we’ll help one another Lets answer these points by writing Yes/No/Don’t know I’ll start first:
The Prophet (Pbuh) revealed his Prophethood at the age of 40 year as instructed by Allah (swt). [Yes/No]
Musa Alahi salam traveled 40 years in the desert. [Yes/No]
Musa spent 40 days on Mount Sinai where he received the 10 commandments. [Yes/No]
Prophet Ibrahim spent 40 days in a fire and lived because Allah made the fire like flowers. ** [Yes/No]**
Prophet Yunus was in a whales mouth for 40 days. [Yes/No]
On the 40th ayat of surah baqarah Allah changes the topic. [Yes/No]
Forty was the number of days that Prophet Ilyas spent in the wilderness before God appeared to him in a cave on Mount Horeb. [Yes/No]
Forty was the number of days that Prophet Isa was tempted in the desert by Satan. [Yes/No]
Muhammad (PBUH) was praying and fasting in the cave for 40 days. [Yes/No]
Muhammad (PBUH) then had 40 followers to spread the religion of Islam. [Yes/No]
Prophets Dauud and Suleiman each ruled for forty years. [Yes/No]
Regarding the flood that Noah encountered, it is said that for forty days water continued to pour from the heavens and to stream out over the earth. [Yes/No]
Prophet Isa walked the desert and fasted in the wilderness for forty days. [Yes/No]
There is also a hadith from Prophet Mohammad (PBUH) that the prayers of a person who gossips would not be accepted for forty days and nights. (Al-Kafi, Vol. 6, p. 400) [Yes/No]
Imam Ali has narrated from Prophet Mohammad (PBUH) that one who memorizes and preserves forty hadith relating to their religious needs shall be raised by Allah as a learned scholar on the Day of Resurrection. [Yes/No]
It is said that a person’s intellect attains maturity in forty years, everyone according to his own capacity. [Yes/No]
It is believed that one who assists a blind man for forty steps becomes worthy of entering heaven. [Yes/No]
Imam Baghir has said: “The prayers of someone who drinks wine are not accepted for forty days.” [Yes/No]
Believers have also been encouraged to devote themselves to God Almighty for forty days to see the springs of wisdom break forth from their hearts and flow from their tongues. [Yes/No]
The Prophet (Pbuh) revealed his Prophethood at the age of 40 year as instructed by Allah (swt). Yes]
Musa Alahi salam traveled 40 years in the desert. [Don't Know]
Musa spent 40 days on Mount Sinai where he received the 10 commandments. [Yes]
Prophet Ibrahim spent 40 days in a fire and lived because Allah made the fire like flowers. ** [Don't know]**
Prophet Yunus was in a whales mouth for 40 days. [Don't Know]
On the 40th ayat of surah baqarah Allah changes the topic. [Don't Know]
Forty was the number of days that Prophet Ilyas spent in the wilderness before God appeared to him in a cave on Mount Horeb. [Don't Know]
Forty was the number of days that Prophet Isa was tempted in the desert by Satan. [Don't Know]
Muhammad (PBUH) was praying and fasting in the cave for 40 days. [Yes]
Muhammad (PBUH) then had 40 followers to spread the religion of Islam. [Yes]
Prophets Dauud and Suleiman each ruled for forty years. [Don't Know]
Regarding the flood that Noah encountered, it is said that for forty days water continued to pour from the heavens and to stream out over the earth. [Yes]
Prophet Isa walked the desert and fasted in the wilderness for forty days. [Don't Know]
There is also a hadith from Prophet Mohammad (PBUH) that the prayers of a person who gossips would not be accepted for forty days and nights. (Al-Kafi, Vol. 6, p. 400) [Don't know]
Imam Ali has narrated from Prophet Mohammad (PBUH) that one who memorizes and preserves forty hadith relating to their religious needs shall be raised by Allah as a learned scholar on the Day of Resurrection. [Yes]
It is said that a person’s intellect attains maturity in forty years, everyone according to his own capacity. [Don't Know]
It is believed that one who assists a blind man for forty steps becomes worthy of entering heaven. [Don't Know]
Imam Baghir has said: “The prayers of someone who drinks wine are not accepted for forty days.” [Don't Know]
Believers have also been encouraged to devote themselves to God Almighty for forty days to see the springs of wisdom break forth from their hearts and flow from their tongues. [Don't Know]
P.S. "Don't know" means I heard but haven't read with references.
Psyah bhai for explanation. Let me write same points in different way. I think this is how we can test our level of knowledge and in case we are wrong than I hope we’ll help one another 
Lets answer these points by writing Yes/No/Don’t know