Muslim 4/2086, the meaning of sami`a sāmi`un (who listens has heard) is that 'a witness has witnessed our praise of Allah due to His blessings and favor upon us.' It could also be read samma`a sāmi`un, in which case it means 'one who has heard this statement of mine will convey it to another and he will say it as well.' This is due to the attention given to the Thikr (remembrance of Allah) and supplications made during the early morning hours. The meaning of his saying 'Our Lord, be with us and bestow Your favor upon us' is: 'Our Lord, protect us and guard us. Bless us with Your numerous bounties, and avert from us every evil.' See An-Nawawi, Sharh Sahih Muslim 17/39.
Hisnul Muslim 215