Ali bin Abdur Rahman Mu'awiyah narrates: Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) saw me playing with pebbles during prayer. When he completed the prayer, he forbade me from doing so, and said: Do as the Prophet Muhammad (peace be upon him) used to do. He informed: When the Prophet Muhammad (peace be upon him) would sit during prayer, he would place his right palm on his right knee. He would gather all his fingers and point with the finger next to the thumb. He would place his left palm on his left knee.
Hadith Referenceصحیح ابن حبان / كتاب الصلاة / 1942
Hadith Gradingفضيلة الشيخ الإمام محمد ناصر الدين الألبانيصحيح - «صحيح أبي داود» (907): م.فضيلة الشيخ العلّامة شُعيب الأرناؤوطإسناده صحيح على شرط مسلم، رجاله رجال الشيخين غير علي بن عبد الرحمن المعاوي، فإنه من رجال مسلم