I, along with a group of people, gave the pledge of allegiance to Allah's Messenger (ﷺ). He said, "I take your
Pledge on the condition that you (1) will not join partners in worship with Allah, (2) will not steal, (3)
will not commit illegal sexual intercourse, (4) will not kill your offspring, (5) will not slander, (6) and
will not disobey me when I order you to do good. Whoever among you will abide by his pledge, his
reward will be with Allah, and whoever commits any of those sins and receives the punishment in this
world, that punishment will be an expiation for his sins and purification; but if Allah screens him, then
it will be up to Allah to punish him if He will or excuse Him, if He will."
Sahih al-Bukhari Book 97, Hadith 94
I met Thauban, the freed slave. of Allah's Messenger (ﷺ), and asked him to tell me about an act for which, if I do it, Allah will admit me to Paradise, or I asked about the act which was loved most by Allah. He gave no reply. I again asked and he gave no reply. I asked him for the third time, and he said: I asked Allah's Messenger (ﷺ) about that and he said: Make frequent prostrations before Allah, for you will not make one prostration without raising you a degree because of it, and removing a sin from you, because of it. Ma'dan said that then lie met Abu al-Darda' and when he asked him, he received a reply similar to that given by Thauban.
Sahih Muslim Book 4, Hadith 255