Sayyiduna Anas bin Malik (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) performed the obligatory prayer sitting on the ground, and he performed the voluntary prayer on the ground and made gestures in it.
Abu Ya'la recorded it; its chain contains Hafs bin Umar, the judge of Aleppo, who is da'if (weak).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 2898