All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
Abu Hurayrah narrated that the Prophet said: "Is any of you unable to move forward or backward or to his right or to his left, i.e. while performing supererogatory prayers after the obligatory ones." [Abu Daawood and Ibn Maajah]
Moreover, 'Umar Ibn Al-'At'a narrated that Naf'i Ibn Jubayr, sent him to Al-Saa'ib, the son of the sister of Namr, with a view to asking him about what he had seen in the prayer of Mu'aawiyah, and he said: "Yes, I observed the Friday prayer along with him in Maqsura and when the Imaam pronounced the Salaam I stood up in my place and observed the Sunnah prayer. As he entered (the apartment) he sent for me and said: Do not repeat what you have done. Whenever you attend the Friday prayer, do not perform a supererogatory prayer till you talk or get out for the Messenger of Allaah had ordered us to do this and not to combine two (different types of) prayers without talking or going out."
An-Nawawi said: "It is evidence for Shaafi'i scholars that it is desirable to perform supererogatory prayers in a place other than the place where one had observed the obligatory prayer. It is better to perform the voluntary prayers in one's house, otherwise in the mosque but not at the same place where one had performed the obligatory prayer. The reason is to multiply the places of prostrations and distinguish between an obligatory prayer and a supererogatory one. The words in the above Hadith: "...till you have talked..." prove that the separation between obligatory and supererogatory prayers may occur only by talking, even though it is better to change the place for the above evidence."
Ibn Taymiyyah said: "It is a Sunnah to separate an obligatory or Friday prayer from supererogatory prayers for the Hadeeth that the Prophet prohibited joining a prayer with another one till one separates between them by moving from that place or talking."
Allaah Knows best.