Abu Hurairah (May Allah be pleased with him) reported:
Messenger of Allah (ﷺ) said, "Should I not direct you to something by which Allah obliterates the sins and elevates (your) ranks." They said: "Yes, O Messenger of Allah". He said, "Performing Wudu' properly, even in difficulty, frequently going to the mosque, and waiting eagerly for the next Salat (prayer) after a Salat is over; indeed, that is Ar- Ribat".[Muslim].
Arabic/English book reference: Book 1, Hadith 131