Fiqh-us-Sunnah Volume 4, Funerals and Dhikr, Fiqh 4.110A.

Ibn ‘Abbas reported, “Once, when I recited the verses of the Qur’an, ‘O you people! Eat of what is on earth, lawful and good’ (2.168) in the presence of the Prophet, peace be upon him. Sa’d b. Abi Waqqas got up and said, ‘O Messenger of Allah! Ask Allah to make me one whose supplication is heard.’ At this the Prophet, peace be upon him, said, ‘O Sa’d, consume lawful things and your supplications will be heard, and by Him in Whose hands is the soul of Muhammad, when a man puts into his stomach a morsel of what is forbidden his prayers are not accepted for forty days, and a servant of Allah whose body is nourished by usury or by what is forbidden becomes more deserving of the Hell fire.” (Al-Hafiz b. Marduwiyah)

Abu Hurairah reported that the Prophet, peace be upon him, said, “O people, Allah is Good and He, therefore, accepts only that which is good. And Allah commanded the believers as He commanded the Messengers by saying, ‘O Messengers, eat of the good things, and do good deeds; verily I am aware of what you do,’ Qur’an 23.51 and He said: ‘O those who believe, eat of the good things that We gave you’.” Qur’an 2.172 The Prophet, peace be upon him, then made mention of a person who travels widely, his hair dishevelled, and covered with dust. “He lifts his hands and makes supplication, ‘O Lord, O Lord,’ but his diet is unlawful, his drink is unlawful, and his clothes are unlawful, and his nourishment is unlawful. How then can his supplication be accepted?” (Muslim and Ahmad)