It was narrated that 'Abdur-Rahman bin Yazid said

"The people asked 'Abdullah too many questions one day, and 'Abdullah said: 'There was a time when we did not pass so many judgments, but now that time is over. Now Allah, the Mighty and Sublime, has decreed that we reach a time when, as you see, (we are asked to pass many judgments). Whoever among you is asked to pass a judgment after this day, let him pass judgment according to what is in the Book of Allah. If he is faced with a matter that is not mentioned in the Book of Allah, let him pass judgment according to the way His Prophet passed judgment. If he is faced with a matter that is not mentioned in the Book of Allah and concerning which His Prophet did not pass judgment, then let him pass judgment according to the way the righteous passed judgment. If he is faced with a matter that is not mentioned in the Book of Allah, and concerning which His Prophet and the righteous did not pass judgment, then let him strive to work it out, and let him not say 'I am afraid, I am afraid.' For that which is lawful is clear and that which is unlawful is clear, and between them are matters which are not as clear. Leave that which makes you doubt for that which does not make you doubt.'"