He keeps the House on his left and circumambulates (1) it seven times, never cutting through the Hijr during his tawaf, for (2) most of the Hijr is part of the House itself, and Allah has commanded that one go around it, not inside it.
He is to touch none of the corners except the two Yemeni ones (3), not the two Levantine corners, for the Prophet—may Allah bless him and grant him peace—touched only those two. They stand upon the foundations laid by Abraham, whereas the other two lie within the House. Thus, the Black Corner is both touched and kissed, the Yemeni Corner is touched but not kissed, and the remaining two are neither touched nor kissed.
Istilam is simply wiping the corner with one’s hand.
As for the other sides of the House, the Station of Abraham, every other mosque on earth and their walls, and the graves of the prophets and the righteous—such as the chamber of our Prophet Muhammad (4), the Cave of Abraham, and the place where our Prophet—may Allah bless him and grant him peace—used to pray