The obligation is what is more appropriate to do than to leave, with the prohibition of leaving it, established by an unequivocal evidence without any doubt: like the Quran, and the mutawatir Sunnah, if no specific context is attached to them: and like consensus, if it is not transmitted through individual reports: and like the analogy that is explicitly stated with its reason. Its ruling is: that the doer is rewarded, the one who leaves it without excuse is punished, and the denier is disbelieved; because it is necessary in knowledge and action. It is called (the cognitive obligation). See: Al-Tawdeeh li Sadr al-Shari'ah, 2/257-263, and Kashf al-Asrar, 1/84, and Rad al-Muhtar, 1/102-103, 1/477.