Dr. Zakir Naik refers to Muhammad S.A.W....

Think not of those who are slain in Allah's way as dead. Nay, they live, finding their sustenance in the presence of their Lord; They rejoice in the bounty provided by Allah. And with regard to those left behind, who have not yet joined them (in their bliss), the (martyrs) glory in the fact that on them is no fear, nor have they (cause to) grieve. „
—Qur'an, 2:214

In case you missed, sustenance means
1 a: means of support, maintenance, or subsistence : living b: food , provisions ; also : nourishment
2 a: the act of sustaining : the state of being sustained b: a supplying or being supplied with the necessaries of life
3: something that gives support, endurance, or strength