(a) It is narrated from Salim Abu al-Nadr that the Prophet (peace and blessings be upon him) would set out toward the mosque after the call (adhan). When he saw that the people in the mosque were few, he would sit down until the people gathered; then he would lead the prayer. And when he saw that the people had all gathered, he would have the prayer begin.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 2283