The one performing Umrah does not stop the talbiyah until he begins the tawaf

Mujahid (may Allah have mercy on him) says: Sayyiduna Ibn Abbas (may Allah be pleased with them both) used to say the talbiyah in Umrah until he touched the Black Stone, then he would stop. And Sayyiduna Ibn Umar (may Allah be pleased with them both) used to say the talbiyah in Umrah until, when he saw the houses of Makkah, he would stop the talbiyah and turn to takbir and remembrance (dhikr) until he touched the Black Stone.

Abd al-Malik says that Ata was asked: "When should the one performing Umrah stop the talbiyah?" He said: "Ibn Umar (may Allah be pleased with them both) says: When he enters the Haram. And Ibn Abbas (may Allah be pleased with them both) says: When he touches the Black Stone." I said: "O Abu Muhammad, which of the two do you prefer?" He said: "The view of Ibn Abbas (may Allah be pleased with them both)."

Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) says: The one performing Umrah should keep saying the talbiyah until he begins the tawaf, whether he touches (the Black Stone) or does not touch it.

Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) says that the Prophet (peace and blessings be upon him) would keep saying the talbiyah in Umrah until he touched the Black Stone, and in Hajj until he stoned the Jamrah.

Sayyiduna Ibn Abbas (may Allah be pleased with them both) says that the Prophet (peace and blessings be upon him) kept saying the talbiyah in Umrah until he touched the Black Stone.
Imam al-Shafi'i (may Allah have mercy on him) said: But we were wary of his (Ibn Abi Layla's) narration, because we found the huffaz of Makkah stopping it at Ibn Abbas (mawquf).
Raising it (to the Prophet) is an error. This Ibn Abi Layla made many mistakes, especially when narrating from Ata, where he erred often; the scholars of transmission declared him da'if (weak) despite his great standing in fiqh. It has also been narrated from al-Muthanna bin al-Sabbah from Ata as marfu' (attributed to the Prophet), and its chain is weaker than what we have mentioned.

Amr bin Shu'ayb narrates from his father, and he from his grandfather (may Allah be pleased with him), that: "The Prophet (peace and blessings be upon him) performed three Umrahs, and each time he would stop the talbiyah only when he touched the Black Stone."
The Shaykh (may Allah have mercy on him) said: It has also been reported from al-Hajjaj, from Ata, from Ibn Abbas as a marfu' report, and al-Hajjaj bin Artat is not used as evidence. It has also been narrated from Abu Bakrah as a marfu' report "that he went out with him on one of his Umrahs, and he did not stop the talbiyah until he touched the Black Stone"; its chain is weak.

Sayyiduna Abu Bakrah (may Allah be pleased with him) said that the Messenger of Allah (peace and blessings be upon him) set out on one of his Umrahs, and I set out with him, and he did not stop the talbiyah until he had touched the Black Stone.
This chain is not strong, and Allah knows best.