Being Cautious of the Doubtful

On the authority of Abu Muhammad al-Hasan ibn 'Alee ibn Abee Taalib (radiAllaahu 'anhumaa), the grandson of the Messenger of Allaah (sallAllaahu alayhi wa sallam), and the one much loved by him, who said: I memorised from the Messenger of Allaah (sallAllaahu alayhi wa sallam):

Leave that which makes you doubt for that which does not make you doubt. [It was related by at-Tirmidhee and an-Nasaa'ee, with at-Tirmidhee saying that it was a good and sound (hasan saheeh) hadeeth.]

Explanation of Hadeeth 11
Its meaning returns back to what has already been said regarding the meaning of Hadeeth 6, that is "The Halaal is Clear, and the Haraam is Clear, and between them are Doubtful matters". And it has been narrated in another hadeeth that the Messenger sallAllaahu alayhi wa sallam said:

"The slave will never be able to attain the ranks of the Muttaqoon (pious ones) until he leaves those things which do not seem to have any harm in them, fearing that they may indeed be harmful/unlawful."
And this would be a higher station than that indicated by the first hadeeth.

And Allaah knows best.

Summary
That it is essential to leave the doubtful things
That one cannot continue doing the doubtful when one knows of an alternative with certainty