Sayyidah Aishah (may Allah be pleased with her) said that the Prophet (peace and blessings be upon him) said: "Have you not seen that when your people built the Ka'bah, they fell short of the foundations of Ibrahim?" I said: "O Messenger of Allah, why do you not restore it to the foundations of Ibrahim?" So he (peace and blessings be upon him) said: "Were it not that your people's time of disbelief is so recent, I would have done so." Then Abdullah bin Umar (may Allah be pleased with them both) said: "If Aishah (may Allah be pleased with her) heard this from the Prophet (peace and blessings be upon him), then I think that the Prophet (peace and blessings be upon him) left touching the two corners next to the Hijr only because they are not on the foundations of Ibrahim."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الحج / 9313