It is narrated from al-Aswad that Sayyiduna Abdullah (may Allah be pleased with him) used to offer the Maghrib prayer at sunset, and he would say: By the One besides whom there is no god! This is the (true) time of this prayer.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2107