Abu Hurairah (May Allah be pleased with him) reported: The Messenger of Allah (sallallaahu ’alayhi wa sallam) said, “Everyone among you will be deemed to be occupied in Salat (prayer) constantly so long as Salat (the prayer) detains him (from worldly concerns), and nothing prevents him from returning to his family but Salat.”
[Al-Bukhari and Muslim].
Commentary: This Hadith tells us the merits of waiting for Salat. As long as a person sits in mosque waiting for Salat, all his time is reckoned as being in the state of Salat and so eligible for the same reward.
Anas (May Allah be pleased with him) reported: Once the Messenger of Allah (sallallaahu ’alayhi wa sallam) delayed the night prayer (`Isha’) till midnight. He (sallallaahu ’alayhi wa sallam) turned to us after Salat (prayer) and said, “The people slept after performing their Salat, but you who waited, will be accounted as engaged in Salat throughout the period of your waiting.”
Posted from : Imam Al-Nawawi’s Riyad-us-Saliheen, Chapter 190, The Excellence of waiting for As-Salat (The Prayer) , Published by Dar-us-Salam .