The Yemeni corner is so called because it is in the direction of Yemen. It is located at the southwest corner of the Ka`bah. A pilgrim in Hajj or `Um
rah can rub the Yemeni corner with the right hand, if possible, and say “Allahu Akbar” just once when touching it.
The late Muslim scholar Sheikh Ibn Baz, the former Mufti of Saudi Arabia, stated: “There is no textual evidence, as far as I know, indicating that a pilgrim should point at the Yemeni corner. It is reported that he should rub it if possible, but not kiss it. At touching it, a pilgrim should say “Bismillah wa Allahu Akbar” or “Allahu Akbar”. If it is difficult to touch the Yemeni corner, a pilgrim should not struggle to reach it. Rather, he should go on with his Tawaf without pointing at it, nor saying “Allahu Akbar” on passing by it, as neither the Prophet (peace and blessings be upon him) nor any of his Companions (may Allah be pleased with them all) did so.
As for the number of takbir, a pilgrim says it once, and there is nothing indicating repeating it, according to my knowledge.
During Tawaf, a pilgrim can make as much dhikr and du`aa’ as he can. At the end of each circle around the Ka`bah, he recites the du`aa’ which the Prophet (peace and blessings be upon him) used to recite then, that is, to say: “O Lord! Give us good in this world and good in the Hereafter and save us from the torment of the Fire.” However, making dhikr and du`aa’ (including that mentioned above) is Sunnah and not obligatory.”