Unays bin Sawwar Abu Ziyad al-Jarmi said that his father related: Abu Qilabah and I were sitting at the back of the mosque when Sayyiduna Malik bin al-Huwayrith (may Allah be pleased with him) came in to us and said: "Shall I not tell you how your Prophet (peace and blessings be upon him) used to pray?" We said: Yes. So he went forward and prayed two rak'ahs, keeping them brief. Then Abu Qilabah (may Allah have mercy on him) and I differed about his knees: I said: He kept (his knees) pressed to the ground; and Abu Qilabah said: He kept (them) apart.
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 16694