Sayyiduna Qays bin Sa'd al-Ansari (may Allah be pleased with him) was the standard-bearer of the Messenger of Allah (peace and blessings be upon him). He intended to perform Hajj, and he combed one side of his head. His slave got up and garlanded his sacrificial animal. Sayyiduna Qays (may Allah be pleased with him) looked, having combed one side of his head, and saw that his sacrificial animal had been garlanded; so he pronounced the talbiyah for Hajj and did not comb the other side of his head.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب قسم الفيء والغنيمة / 13057