Tafsir of Al-Qalam 68:3

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

غير ممنون

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

عطاء غير مجذوذ

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

فلهم أجر غير ممنون

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

غير ممنون

(Without Mamnun) means "Without reckoning.'' And this refers back to what we have said before. The Explanation of the Statement: "Verily, You are on an Exalted Character.'' Concerning Allah's statement,

وإنك لعلى خلق عظيم