Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) said: "There are three things upon which I swear, and a fourth which, if I swore upon it, I hope I would not be sinful and would still be truthful: Allah will not make the one who has a share in Islam like the one who has no share; the Muslim servant who takes Allah as his protecting friend will not be given any protector other than Allah on the Day of Resurrection; and a man who loves a people, Allah will raise him with them. The shares of Islam are three: prayer, zakah and fasting. And the fourth, upon which, if I swore, I hope I would not be sinful: Allah does not conceal the faults of a servant in this world except that He will also conceal them in the Hereafter."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 8768