its a form of "hasad" (jealousy)....
and u shud ask for Allah's refuge from it....
read surah al-falaq for this....
Al-Muwatta by Imam Malik - Hadith 50.2 & 3
Yahya related to me from Malik that Humayd ibn Qays al-Makki said, "A man came to the Messenger of Allah, may Allah bless him and grant him peace, with the two sons of Jafar ibn Abi Talib. He said to their nursemaid, 'Why do I see them so thin?' Their nursemaid said, 'Messenger of Allah, the evil eye goes quickly to them. Nothing stops us from asking someone to make talismans (using ayats of Qur'an) for them, except that we do not know what of that would agree with you.' The Messenger of ,Allah, may Allah bless him and grant him peace, said, 'Make talismans for them. Had anything been able to precede the decree, the evil eye would precede it.' "
Malik related to me from Ibn Shihab that Abu Umama ibn Sahl ibn Hunayf said, ''Amir ibn Rabia saw Sahl ibn Hunayf doing a ghusl and said, 'I have not seen the like of what I see today, not even the skin of a maiden who has never been out of doors.' Sahl fell to the ground. The Messenger of Allah, may Allah bless him and grant him peace, was approached and it was said, 'Messenger of Allah, can you do anything about Sahl ibn Hunayf? By Allah, he can not raise his head.' He said, 'Do you suspect anyone of it?' They said, 'We suspect Amir ibn Rabia.' "
He continued, "The Messenger of Allah, may Allah bless him and grant him peace, summoned Amir and was furious with him and said, 'Why does one of you kill his brother? Why did you not say, "May Allah bless you?" Do ghusl for it.' Amir washed his face, hands, elbows, knees, the end of his feet, and inside his lower garment in a vessel. Then he poured it over him, and Sahl went off with the people, and there was nothing wrong with him."
P.S. I dont know the authencity of these hadith, my source says they r from muwatta but i take no guarantee for them to be right....
"Our Lord! forgive us our sins and anything we may have done that transgressed our duty; establish our feet firmly and help us against those that resist faith." **Quran(3:147)