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 Rubb! My Rubb!' 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?" <b>[Muslim]</b>.

وعن أبي هريرة رضي الله عنه قال‏:‏ قال رسول الله صلى الله عليه وسلم ‏:‏ ‏

‏يا أيها الناس إن الله طيب لا يقبل إلا طيباً، وإن الله أمر المؤمنين بما أمر به المرسلين، فقال تعالى‏:‏ ‏{‏يا أيها الرسل كلوا من الطيباب واعلموا صالحاً‏}‏، وقال تعالى‏:‏ ‏{‏يا أيها الذين آمنوا كلوا من طيبات ما رزقناكم‏}‏ ثم ذكر الرجل يطيل السفر أشعث أغبر يمد يديه إلى السماء ‏:‏ يا رب يارب، ومطعمه حرام، ومشربه حرام، وملبسه حرام، وغذي بالحرام فأنى يستجاب لذلك‏!‏‏؟‏‏

‏ ‏(‏‏(‏رواه مسلم‏)‏‏)‏‏.‏