قَالَ أَبُو جَعْفَرٍ (ع): وَ الْحَجْرُ كَالْمِيثَاقِ وَ إِسْتِلاَمُهُ كَالْبَيْعَةِ وَ كَانَ إِذَا إِسْتَلَمَهُ قَالَ: أَللٌّهُمَّ أَمَانَتِي أَدَّيْتُهَا وَ مِيثَاقِي تَعَاهَدَتْهُ لِيَشْهَدَلِي عِنْدَكَ بِالْبَلاَغِ.

 
Abu Ja’far [Imam Muhammad Ibn ‘Ali al-Baqir] (peace be upon him) has said, “The Hajr (Hajrul Aswad – the Black Stone) is like the pledge (of Allah) and rubbing the hand over it is like making a pledge of allegiance (to Allah).”  Whenever the Imam (peace be upon him) would rub his hand over the Hajrul Aswad he used to say:
 

أَللٌّهُمَّ أَمَانَتِي أَدَّيْتُهَا وَ مِيثَاقِي تَعَاهَدَتْهُ لِيَشْهَدَلِي عِنْدَكَ بِالْبَلاَغِ

“O’ Allah!  I have fulfilled my trust and have renewed my pledge so that it (the Hajr al-Aswad) can bear witness that surely I have fulfilled my responsibility.”