What is the significance of the Black Stone?

The Black Stone descended from Paradise and was whiter than milk, but the sins of the children of Adam blackened it. On the Day of Resurrection, it will come with two eyes and a tongue, testifying for those who genuinely touched it. The first thing a circumambulator does is to touch or kiss the Stone, or to touch it with their hand and then kiss their hand, or to touch it with something and then kiss that object, or to point to it and say "Allahu Akbar" if unable to reach it. Wiping the Stone expiates sins. It is not permissible to harm Muslims near the Stone.