It is narrated from Sayyiduna Ibn Mas'ud (may Allah be pleased with him) that the Prophet (peace and blessings of Allah be upon him) used to sit between the two rak'ahs as if he were sitting on a hot stone.
Hadith Referenceمسند احمد / مسند المكثرين من الصحابة / 4074
Hadith Gradingحکم دارالسلام:إسناده ضعيف لانقطاعه، أبو عبيدة لم يسمع من ابن مسعود.