Rashid bin Yasar (may Allah be pleased with him) said: I bear witness concerning five men from among those who pledged allegiance to the Prophet (peace and blessings be upon him) under the tree, among them Mirdas or Ibn Mirdas (may Allah be pleased with him), that they used to pray two rak'ahs before Maghrib.
[Da'if (weak). Abu Nu'aym in Ma'rifat al-Sahabah: 6198]
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 4503