Maliks Muwatta Book 8, Hadith Number 10.
Section : Doing the Prayer Again with the Imam.
Yahya related to me from Malik from Nafi that a man asked Abdullah ibn Umar, “Sometimes I pray in my house, and then catch the prayer with the imam. Should I pray with him?” Abdullah ibn Umar said to him, “Yes,” and the man said, “Which of them do I make my prayer?” Abdullah ibn Umar said, “Is that up to you? It is up to Allah. He will decide on whichever of them He wishes.”