233. Is It Permissible To Pray The Nawafil Or Sunnah In Sitting Position?

It is permissible to pray the nawaafil and Sunnah prayers sitting with no excuse, and the prayer is valid. 

But keep in mind that the reward for that is reduced to HALF the reward of one who stands. 

Proof:

Abd-Allaah ibn ‘Amr radhi Allaahu anhu said: 

“I was told that the Messenger of Allaah Sal Allaahu Alaiyhi wa Sallam said: 

“The prayer of a man who sits is half of the prayer of a man who stands.” 

I came to him and found him praying sitting. 

I put my hand on his head and he said, ‘What is the matter, O ‘Abd-Allaah ibn ‘Amr?” 

I said, “I was told, O Messenger of Allaah that you said, ‘The prayer of a man who sits is half of the prayer of a man who stands,’ and you are praying sitting.” 

He said, 

“Yes, but I am not like one of you.” (Muslim)

Imaam an-Nawawi said: 

“This hadeeth is to be understood as referring to a naafil prayer offered sitting when one is able to stand. 

This brings half the reward of a prayer offered standing. 

But if a person offers a naafil prayer sitting down because he is unable to stand, then the reward is NOT reduced; 

rather it will be the SAME as one who stands. 

With regard to OBLIGATORY prayers, if a person prays sitting down when he is able to stand, his prayer is NOT VALID and he will not be rewarded, rather he is sinning.” (Sharh Muslim)

And Allaah knows best