Musannaf Ibn Abi Shaybah

It is narrated from Hazrat Ata that Hazrat Ibn Umar (may Allah be pleased with them) came and performed Tawaf and Sa'i, then stayed for four or five days without Ihram, then on the tenth he donned the Ihram for Hajj. Then, when he came the second time, he stayed without Ihram until the eighth of Dhul-Hijjah, then on the eighth he donned the Ihram for Hajj when he let the camels go towards Mina. Hazrat Ata says that this is preferable in my view.