What was the special invocation that Prophet Muhammad (peace be upon him) wished to be granted as intercession for his followers on the Day of Judgment?
 Narrated Abu Huraira:                     Allah's Apostle said, "For every Prophet there is one invocation which is definitely fulfilled by Allah, and I wish, if Allah will, to keep my that (special) invocation as to be the intercession for my followers on the Day of Resurrection."