Ibn Ishaq reported,

He related to me concerning how the Messenger of Allah ﷺ would spread his left thigh in the middle of the prayer and at its end, sitting on his left hip, placing his left hand on his left thigh, setting his right foot upright, placing his right hand on his right thigh, and raising his index finger by which he would affirm the oneness of his Lord .Imran bin Abu Anas, the brother of Banu Amir bin Luayy, who was trustworthy, reported from Abu Qasim Miqsam, the freed slave of Abdullah bin Harith bin Nawfal, who said, A man from the people of Madinah told me, "I prayed in the mosque of Banu Ghifar. When I sat during my prayer, I spread out my left thigh and raised my index finger. Khafaf bin Ima bin Rahdah al-Ghifari, who had been a companion of the Messenger of Allah ﷺ, saw me doing this.When I had finished my prayer, he said to me, 'My son, why did you raise your finger like that?'I replied, 'What is wrong with it? I have seen people doing it.'He said, 'You have done what is correct. The Messenger of Allah ﷺ used to do that when he prayed. The polytheists used to say, Muhammad is only doing this with his finger to cast a spell with it. They lied. The Messenger of Allah ﷺ only did that to affirm the oneness of his Lord .'"

قال حدثنا يعقوب بن إبراهيم قال حدثنا أبي

عن ابن إسحاق قال

حدثني عن افتراش رسول الله ﷺ فخذه اليسرى في وسط الصلاة وفي آخرها وقعوده على وركه اليسرى ووضعه يده اليسرى على فخذه اليسرى ونصبه قدمه اليمنى ووضعه يده اليمنى على فخذه اليمنى ونصبه أصبعه السبابة يوحد بها ربه عز وجل عمران بن أبي أنس أخو بني عامر بن لؤي وكان ثقة عن أبي القاسم مقسم مولى عبد الله بن الحارث بن نوفل قال حدثني رجل من أهل المدينة قال صليت في مسجد بني غفار فلما جلست في صلاتي افترشت فخذي اليسرى ونصبت السبابة قال فرآني خفاف بن إيماء بن رحضة الغفاري وكان له صحبة مع رسول الله ﷺ وأنا أصنع ذلك قال فلما انصرفت من صلاتي قال لي أي بني لم نصبت إصبعك هكذا قال وما تنكر رأيت الناس يصنعون ذلك قال فإنك أصبت إن رسول الله ﷺ كان إذا صلى يصنع ذلك فكان المشركون يقولون إنما يصنع هذا محمد بإصبعه يسحرها وكذبوا إنما كان رسول الله ﷺ يصنع ذلك يوحد بها ربه عز وجل