al-Ahkam fi Usul al-Ahkam, By Ibn Hazam al-Zahiri, Publish, Dar al Hadith, Beirut/Lebanon
Ibn Hazam al-Zahiri on Bidah He Said: Bid`ah in the Religion is everything that did not come to us in the Qur’an nor from the Messenger of Allah , except that one is rewarded for some of it and those who do this are excused if they have good intentions. Of it is the rewardable and excellent (hasan), namely, what is originally permitted (ma kana as.luhu al-ibah.a) as was narrated from `Umar (ra): “What a fine bid`ah this is!” Such refers to all good deeds which the texts stipulated in general terms of desirability even if its practice was not fixed in the text. And of it is the blameworthy for which there is no excuse such as what has proofs against its invalidity. [al=Ahkam fi Usul al-Ahkam, Volume 001, Page No. 47]