Proof–>>Waail ibn Hujr narrates that, “I prayed with the Prophet and he placed his right hand upon his left on his chest.” (Saheeh ibn Khuzaimah, 1/243).
Imaam Ibn Khuzaimah, in relation to his Saheeh Ibn Khuzaimah, states at the very beginning the condition that, “This is a compilation of authentic ahadeeth which go right back to the Prophet with authentic and complete chains of narration. No narrator in the chains is unknown nor is there any broken chain of narration.” (Ibn Khuzaimah, 1/2).
—>>This proves that this narration is absolutely authentic and free from deficiency according to Imam Ibn Khuzaymah. Further it is mentioned by Imaam Nawawee in his explanation of Saheeh Muslim, (4/115, Egyptian print), in Sharhul-Muhazzab (3/315), Haafidh ibn Sayyid in An-Naas in An-Nafkhush Shuzaa (2/211), Haafidh Shamsud-Deen ibn Abdul Haadee al-Maqdisee in Al-Muharar fil-Hadeeth, (p. 44), Haafidh Zailee in Nasbur-Raayah (1/314), Ibn Hajr in Fathul-Baari (2/224), Talkhees al-Habeer (1/224, Egyptian), Ad-Darayah Fee Takhreej Ahadeeth al-Hidaayah (1/128, Egyptian), and in Buloogh al-Maraam (p. 55), Aliaamah Ainee Hanafee in Umdatal-Qaaree (5/379, Al-Muneeriyyah Print), Imaam Shawkaanee in Naylal-Awtaar(Zn 15), Aliaamah Mujadiddud-Deen Fairozabaadee in Safaras-Sa’dah, Aliaamah al-Murtada az-Zubaidee Hanafee in Aqoodul-Jawaahir al-Muneefah (1/59) – (these) and others have all reported this hadeeth.
Further, Imaam Ibn Sayyid an-Naas, Haafidh Ibn Hajr, Aliaamah Ainee and Aliaamah Shawkaanee have all declared this narration authentic. Likewise, Mulla Qaaim Sindhee in his Risaalah Fauz al-Kiraam and Muhammad Hashim Sindhee in Dirham us-Surrah have stated this hadeeth to be authentic (saheeh).
Also, Ibn Nujaym Hanafee in Al-Bahr ar-Raqaa’iq, Allaamah Abul Hasan al-Kabeer as-Sindhee in Fathul-Wadeed Sharh Abee Dawood, Aliaamah Muhammad Hayaat Sindhee in his Fathul-Ghafoor and Shaikh Abu Turaab Raashidullaah Shah Raashidee in his Darjud-Duroor have all stated this hadeeth to be authentic (saheeh). …
It can be seen then that this hadeeth in its chain of narration and meaning, is clear as it informs us that the Sunnah of the Prophet is to place the hands upon the chest in the prayer.