Sayyiduna Abu Hurayrah (may Allah be pleased with him) reports this saying of the Prophet (peace and blessings be upon him): "Whoever has three daughters and provides for them, shelters them and looks after them, Paradise becomes binding for him." We said: "What if there are two daughters?" The Prophet (peace and blessings be upon him) said: "Even if there are two daughters (the same reward is gained)." We said: "What if there is one?" The Prophet (peace and blessings be upon him) said: "Even if there is one (the same reward is gained)."
Imam Tabarani recorded it in al-Mu'jam al-Awsat, and its chain contains narrators whom I do not know.