Question
Can I perform voluntary prayers in a sitting position while only using head movements? I did this in the past, so am I required to make up these prayers?
Answer
In the Name of Allah, the Most Merciful and Compassionate
It is permissible to perform voluntary prayers in a sitting position (Qa’idan). However, one’s prostration must be on the ground – head movements do not suffice unless one is unable to prostrate due to sickness. [Tahtawi/Shurunbulali, Hashiyat Maraqi al-Falah]
Performing the prayer sitting with head movements is only allowed for the traveler performing voluntary prayers in a conveyance or vehicle. [Ibid.]
Making Up Invalidated Voluntary Prayers
Any voluntary prayer that a person commences is obligatory to see to its sound completion. Thus, if one starts a voluntary prayer and invalidates the prayer, it becomes obligatory to make up the prayer. [Ibid.]
That said, the basis is that you would have to make up any voluntary prayers in which you used head gestures in place of the prostration. That is unless a person did this due to sickness and inability to prostrate or when traveling. [Ibid.]
Undue Hardship
As a result of this ruling, you may find yourself in great difficulty and undue hardship because of the tremendous amount of voluntary prayers you must make up. In that case, you may consider the opinion of Imam al-Shaf’i that invalid voluntary prayers do not require making up. [Ahmad al-Asbhani, Matn Ghaya wa al-Taqrib (Abu Shuja’)]
If the amount of prayers is not a lot, it is best to estimate the number of prayers and then proceed to make them up, which is ideal. [Ibid.]
That said, regardless of which of the two above options you choose to implement, you should carry on, from here on out, performing voluntary prayers with a complete prostration on the ground. [Ibid.]
Hope this helps
Allah knows best
[Shaykh] Yusuf Weltch
Checked and Approved by Shaykh Faraz Rabbani