(a) It is narrated from Sayyiduna Anas bin Malik (may Allah be pleased with him) that when the mu'adhdhin called the adhan, the Companions (may Allah be pleased with them) of the Messenger of Allah (peace and blessings be upon him) would hurry toward the pillars to pray behind them, until the Messenger of Allah (peace and blessings be upon him) came out. The Companions (may Allah be pleased with them) would also pray two rak'ahs before Maghrib, and there was nothing between the adhan and the iqamah.
(b) Uthman bin Umar narrates from Shu'bah that in the Maghrib prayer there was a short time between the adhan and the iqamah.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2281