It is narrated from Umm Salamah (may Allah be pleased with her) that the Messenger of Allah (peace and blessings be upon him) taught me: "At the time of the Maghrib adhan, say:
'Allahumma inna hadha iqbalu laylika wa idbaru naharika wa aswatu du'atika faghfir li' (O Allah, indeed this is the coming of Your night, the departure of Your day and the voices of Your callers, so forgive me)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1935