Musannaf Ibn Abi Shayba 3:6106

Hushaym narrated to us, he said: Al-Mughirah informed us, from Ibrahim, that Jundub and Masruq went out intending the Maghrib prayer, and they caught one rak'ah with the Imam. When the Imam performed the taslim, Masruq sat for the second rak'ah, while Jundub did not sit. Jundub recited in the rak'ah that he had caught, while Masruq did not recite. They came to Ibn Mas'ud and mentioned to him what they had done. Abdullah said: "Both of you have done well, but doing as Masruq did is more beloved to me."