الحجر الأسود
The Hajar al-Aswad (الحجر الأسود) is a sacred stone set into the eastern corner of the الكعبة in مكة. Muslims begin and end each circuit of الطواف at this point. النبي Muhammad (PBUH) placed it in its current position during the الكعبة's reconstruction.
The الحجر الأسود is believed by Muslims to date back to the time of Prophet Adam (AS) and was originally white, turning black from absorbing the sins of humanity. When the Quraysh rebuilt the الكعبة, a dispute arose over who should place the stone. Prophet Muhammad (PBUH) resolved it by having representatives of each clan hold a cloth carrying the stone, then placing it himself. The stone has been broken into fragments over the centuries and is now held together by a silver frame.
The الحجر الأسود marks the starting and ending point of الطواف. Kissing or pointing to it is a سنة of النبي Muhammad (PBUH). It is considered a stone from Paradise and will testify on the Day of Judgment for those who touched it with sincerity.
The الحجر الأسود is located at the eastern corner of the الكعبة, marked by a green light. During peak times, kissing or touching the stone is extremely difficult due to crowds. It is سنة to kiss it if possible, touch it, or simply point toward it and say 'Allahu Akbar' from a distance. Each الطواف circuit begins and ends at the الحجر الأسود line.