Muhammad ibn 'Ali informed us, saying: Salih narrated to me, saying: I asked my father, "What is its increase and decrease?" He replied, "Its increase is action, and its decrease is the abandonment of action, such as abandoning prayer, zakat, hajj, and the performance of the obligatory duties; this is what decreases it, while it increases through action." He also said, "If it were complete before its increase, then how could something complete increase? Just as it increases, so too does it decrease. Waki' had previously said, 'Do you consider the faith of al-Hajjaj to be like the faith of Abu Bakr and 'Umar, may Allah have mercy upon them?'"