It is narrated from Sayyiduna Sufyan bin Abdullah Thaqafi (may Allah be pleased with him), he says: I said, "O Messenger of Allah! Tell me something about Islam such that after you (Abu Muawiyah has narrated the words 'after you'), there remains no need to ask anyone else about it." The Prophet (peace and blessings be upon him) said: "Say, 'I believe in Allah,' and then remain steadfast upon it."