It is narrated from Sayyiduna al-Sa'ib bin Yazid (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) used to say: "It is sufficient for a man, when supplicating, to say: O Allah, forgive me, have mercy on me, and admit me into Paradise."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 6640