Ayyub narrates from al-Zuhri that Sayyiduna Uthman bin Affan (may Allah be pleased with him) used to pray the prayer in full at Mina because of the Bedouins, since they came in large numbers; he led four rak'ahs for this purpose, so that they would know that the prayer is four rak'ahs.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 5437