Sayyiduna Usamah (may Allah be pleased with him) said: I was with the Prophet (peace and blessings be upon him). When he reached the mountain pass which the rulers enter, he called for water for ablution and performed ablution. I said: The prayer! He (peace and blessings be upon him) said: "The prayer is ahead of you." When he came to Muzdalifah, he had the iqamah called and prayed Maghrib; the last of the people had not yet arrived when he had the iqamah called and prayed Isha.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9488