Ali bin Abdul-Rahman reported,

Abdullah bin Umar saw me fidgeting with pebbles during prayer. When he finished, he forbade me from doing so and said, "Do as the Messenger of Allah ﷺ used to do."I asked, "How did the Messenger of Allah ﷺ do it?"He replied, "When he sat during prayer, he would place his right palm on his right thigh, close all his fingers, point with the finger next to the thumb, and place his left palm on his left thigh."

Muslim 1311

Sahih

حدثنا يحيى بن يحيى قال قرأت على مالك عن مسلم بن أبي مريم

عن علي بن عبد الرحمن المعاوي أنه قال

رآني عبد الله بن عمر وأنا أعبث بالحصى في الصلاة فلما انصرف نهاني فقال اصنع كما كان رسول الله ﷺ يصنع فقلت وكيف كان رسول الله ﷺ يصنع قال كان إذا جلس في الصلاة وضع كفه اليمنى على فخذه اليمنى وقبض أصابعه كلها وأشار بإصبعه التي تلي الإبهام ووضع كفه اليسرى على فخذه اليسرى

مسلم 1311صحيح
Contents
Reference
Commentary
Ayat
Collection
Sahih Muslim
Book
Mosques and places of prayer
Chapter
Description of sitting in prayer and how to place the hands on the thighs
Numbering
Darussalam 1311
Muslim 1311