Sayyiduna Ka'b bin Malik (may Allah be pleased with him) said: When the twelve men returned from (the first) al-Aqabah, the Messenger of Allah (peace and blessings be upon him) having ordered them to come and meet him (peace and blessings be upon him) the following year with seventy men, we spent a year in which each of us would go to his companion and talk about the pledge, the mounts and the provisions, until seventy of us came and met him (peace and blessings be upon him).
Hadith Referenceالمعجم الكبير للطبراني / باب الكاف / 16251