(a) Nafi' said that Abdullah bin Umar (may Allah be pleased with them both) began the talbiyah from "al-Fur'."
(b) Imam al-Shafi'i (may Allah have mercy on him) said: In our view (and Allah knows best), Abdullah bin Umar (may Allah be pleased with them both) passed by the miqat while he had no intention of Hajj or Umrah; then, when he reached al-Fur', he formed the intention and began the talbiyah from there; or he came to al-Fur' from Makkah or somewhere else, then decided to enter ihram and said the talbiyah from there. And he himself narrates the hadith on the mawaqit from the Messenger of Allah (peace and blessings be upon him).
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 8923