Riyad us Saliheen: Hadith 1058

The Messenger of Allah (ﷺ) said, "Shall I not tell you something by which Allah effaces the sins and elevates the ranks (in Jannah)." The Companions said: "Yes (please tell us), O Messenger of Allah." He said, "Performing the Wudu' properly in spite of difficult circumstances, walking with more paces to the mosque, and waiting for the next Salat (prayer) after a observing Salat; and that is Ar-Ribat, and that is Ar-Ribat."

[Muslim].