What is the ruling on standing for a long time on the starting line of the circumambulation (tawaf) while supplicating, which causes obstruction and harm to those performing tawaf?

Standing at the line opposite the Black Stone should not be prolonged. Instead, the pilgrim (Hajj or Umrah performer) should face the Stone, point to it, say "Allahu Akbar," and then move on. Uttering the intention (niyyah) at this spot, or in any act of worship, is an innovation (bid'ah). It has not been reported that the Prophet (peace be upon him) or his noble Companions ever verbalized their intentions. Allah Almighty knows what is in the intentions, and the servant does not need to declare them aloud.