Sunan Abi Dawud Book 2, Hadith 187
I came while the Prophet (ﷺ) was saying the prayer. I sat down and did not pray along with them. The Messenger of Allah (ﷺ) turned towards us and saw that Yazid was sitting there. He said: Did you not embrace Islam, Yazid? He replied: Why not, Messenger of Allah; I have embraced Islam. He said: What prevented you from saying prayer along with the people? He replied: I have already prayed in my house, and I thought that you had prayed (in congregation). He said: When you come to pray (in the mosque) and find the people praying, then you should pray along with them, though you have already prayed. This will be a supererogatory prayer for you and that will be counted as obligatory.
I said the morning prayer along with the prophet (ﷺ) at Mina. He narrated the rest of the tradition to the same effect.
if one of us prays in his house, then comes to the mosque and finds that the iqamah is being called, and if I pray along with them ( in congregation), I feel something inside about it. Abu Ayyub replied: We asked the Prophet (ﷺ) about it. He said: That is a share from the spoils received by the warriors (i.e. he will receive double the reward of the prayer).