Allah says,

﴿مَآ أَنتَ بِنِعْمَةِ رَبِّكَ بِمَجْنُونٍ ﴾

(You, by the grace of your Lord, are not insane.) meaning -- and all praise is due to Allah -- `you are not crazy as the ignorant among your people claim. They are those who deny the guidance and the clear truth that you have come with. Therefore, they attribute madness to you because of it.'

﴿وَإِنَّ لَكَ لاّجْراً غَيْرَ مَمْنُونٍ ﴾

(And verily, for you will be reward that is not Mamnun.) meaning, `for you is the great reward, and abundant blessings which will never be cut off or perish, because you conveyed the Message of your Lord to creation, and you were patient with their abuse.' The meaning of:

﴿غَيْرُ مَمْنُونٍ﴾

(not Mamnun) is that it will not be cut off. This is similar to Allah's statement,

﴿عَطَآءً غَيْرَ مَجْذُوذٍ﴾

(a gift without an end.) (11:108) and His statement,

﴿فَلَهُمْ أَجْرٌ غَيْرُ مَمْنُونٍ﴾

(Then they shall have a reward without end.) (95:6) Mujahid said,

﴿غَيْرُ مَمْنُونٍ﴾

(Without Mamnun) means "Without reckoning.'' And this refers back to what we have said before.