5. Ali ibn Ibrahim has narrated from his father from Hammad, from Hariz from Muhammad ibn Muslim who has said the following
“I once said to him (the Imam) (a.s.), ‘There is a man who has become ill and has omitted optional Salah (prayer).’ He (the Imam) said, ‘O Muhammad, it is not obligatory Salah (prayer). If he performs, it is a good deed that he does. If he did not do, he is not required to perform it.’”