It was narrated from Abu Sa'eed Khudri that he heard :
The Messenger of Allah say: "Shall I not tell you of something by means of which Allah expiates for sins and increases good deeds?" They said: "Yes, O Messenger of Allah." He said: "Perform ablution properly despite difficulties, increasing the number of steps one takes towards the mosque and waiting for the next prayer after prayer.'" (ES)
English reference (ES): Vol. 1, Book 1, Hadith 427 (ES)
Arabic reference (ES): Book 1, Hadith 462 (ES)