In the name of allah Asalam alikum- I like to know the criterial or ruling regarding fard deeds because some people quote some statements from and say it is fard how to know it. i.e. they say zikr dawam is mentioned in quran so it is fard.likewise isolation from people is mentioned in quran so it is fard likewise an act/deed which is fard near one imam is not fard with another imam. please give me full details as possible because i face these situation frequently.Likewse in my little knowledge of quran there are some orders that are fard and some mustahab likewise some are haram and some are makruh. sohow to know what is what .if we intermix it will leads us to falsehood.May Allah bless you.

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

The scholars put some fundamental rules based on the deduction from the Sharee’ah texts, among these rules are those determined by the majority of the scholars that command implies obligation unless there is evidence to suggest likeability and that prohibition implies impermissibility unless there is evidence to suggest dislikeability…and so forth.

However, there might be a difference of opinion among the scholars in applying such rules on some particulars and there are many reasons for this difference of opinion, among which is that this evidence which implies likeability instead of obligation, or implies dislikeability instead of impermissibility, may not have reached this particular scholar, or that the scholar believes for instance that the command that is related to etiquettes implies desirability, and that the prohibition that is related to the etiquettes implies dislikeability in addition to other reasons.

In regard to the Muslim who reads the statements of the scholars and their differences of opinion, then if he is a student of knowledge, he should look to these statements and their evidence, and the aspects of inference, and examine them and then act according to the opinion he considers to be the most preponderant one. However, if he is a layman, then he should ask the scholar whom he trusts in regard to his religion and knowledge and act according to the Fatwa that this scholar issues to him, without being embarrassed and confused by reading books or moving from one Mufti to another.  

Allaah Knows best.