Sa'id bin al-Musayyib (may Allah have mercy on him) said that the Muhajirun did not pray two rak'ahs before Maghrib, while the Ansar used to pray these two rak'ahs. The narrator said: Sayyiduna Anas (may Allah be pleased with him) used to pray them.
(b) Another narration is from Sayyiduna Abd al-Rahman bin Awf (may Allah be pleased with him); he said: We used to pray two rak'ahs before Maghrib. And he was one of the Muhajirun, so it seems that he (Sa'id) meant others besides him, or most of them.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4498