Abu Hurairah (May Allah be pleased with him) said: The Messenger of Allah ﷺ said, "O people! Allah is Pure and, therefore, accepts only that which is pure. Allah has commanded the believers as He has commanded His Messengers by saying: 'O Messengers! Eat of the good things, and do good deeds'. (23:51) And He said: 'O you who believe (in the Oneness of Allah - Islamic Monotheism)! Eat of the lawful things that We have provided you".'. (2:172). Then he ﷺ made a mention of the person who travels for a long period of time, his hair are dishevelled and covered with dust. He lifts his hand towards the sky and thus makes the supplication: 'My Rabb! My Rabb!' But his food is unlawful, his drink is unlawful, his clothes are unlawful and his nourishment is unlawful, how can, then his supplication be accepted?" Muslim.