And it came to pass on the morrow, that he took a thick cloth, and dipped it in water, and spread it on his face, so that he died: and Hazael reigned in his stead. (2 Kings 8:15)
Probably the coverlet that was at the head of the bed. He spread it on Benhadad’s face, thus suffocating him. Undoubtedly this was done in such a way as to make it appear accidental, or as if the king had died a natural death.