Surah Yunus, Ayat 58-59

Ayat 58. Say(O Muhammad  [SAWW](PBUH): "In the Bounty of Allah, and in His Mercy (i.e. Islam and the Qur'an); -therein let them rejoice." That is better than what (the wealth) they amass.

Ayat 59. Say (O Muhammad   [SAWW](PBUH) to these polytheists): "Tell me, what provision Allah has sent down to you! And you have made of it lawful and unlawful." Say (O Muhammad  [SAWW](PBUH): "Has Allah permitted you (to do so), or do you invent a lie against Allah?" 

Hazrat Hasan bin Ali (May Allah be pleased with them) said: I remember (these words) from Messenger of Allah  [SAWW](PBUH): "Give up what is doubtful to you for that which is not doubtful; for truth is peace of mind and falsehood is doubt". [At-Tirmidhi Hadith # 2518].  

Lesson : as mentioned above in Surah Yunus Ayat 59. "Has Allah permitted you (to do so), or do you invent a lie against Allah?" This Hadith leads us to the conclusion that one must always avoid doubtful things so that he does not do anything unlawful. This message is repeated in another Hadith which says that he who has saved himself from doubts has in fact saved his Faith and honour.