Musnad Ahmad 1193:0

Fatima, the paternal aunt of Abu Ubaydah and the sister of Hudhayfah, narrated: The Messenger of Allah (peace and blessings of Allah be upon him) said: "Whoever performs ablution and performs it well, then prays two rak'ahs, turning to Allah with his heart and his face, Paradise will become mandatory for him." She said: I heard him say that, and I said: "How wonderful this is!" A person who was in front of me said: "What came before it was even more wonderful." I looked, and it was Umar ibn al-Khattab. He said: "I saw you just now, and I know that what came before it is even more wonderful than it. The Prophet (peace and blessings of Allah be upon him) said: 'Whoever performs ablution and performs it well, then says: I bear witness that there is no god but Allah alone, with no partner, and I bear witness that Muhammad is His servant and His Messenger, the eight gates of Paradise will be opened for him; he may enter through whichever of them he wishes.'"