´It was narrated from Ibn 'Abbas:` That the Messenger of Allah began the Talbiyah following the prayer.
Hadith Referenceسنن نسائي / كتاب مناسك الحج / 2755
Hadith Gradingالألبانی:ضعيف | زبیر علی زئی:ضعيف، إسناده ضعيف، ترمذي (819) خصيف: ليس بالقوي،كما قال النسائي فى كتاب الضعفاء و المتروكين (177) وضعفه الجمهور (انظر سنن أبى داود بتحقيقي: 266) انوار الصحيفه، صفحه نمبر 342
This narration is weak, and even if considered authentic, it does not refer to the prayer of entering the state of ihram (i.e., the ihram prayer) as some people assume; rather, it was the Zuhr (noon) prayer after which the Prophet sallallahu alayhi wa sallam recited the talbiyah. Indeed, this is explicitly stated in the following narration.
Source: Sunan Nasa'i: Translation and Benefits by Shaykh Hafiz Muhammad Amin Hafizullah, Page: 2755