Answered by Shaykh Faraz Rabbani
What is the reason for moving to another position after fardh for the sunnah prayer
Walaikum assalam wa rahmatullah,
It is recommendedparticularly for the imamto move to another place to perform the post-fard sunna prayers because of hadiths [such as one related by Imam Muslim] from the Prophet (Allah bless him and give him peace) indicating this.
Among the wisdoms behind this is:
a) having more than one place witness for one on the Day of Judgement;
b) to break the lines of prayer’ so that a late incomer can readily tell that the obligatory prayer is over. [Hashiyat al-Tahtawi, Imdad]
And Allah alone gives success.
Wassalam,