I asked Ibn Abbas about a man pointing with his finger, meaning like this, during the prayer. He said, "That is sincerity."Ibn Abbas also said, "The Messenger of Allah ﷺ commanded us to use the tooth-stick so emphatically that we thought a revelation would come down to him about it. And I saw the Messenger of Allah ﷺ prostrate until the whiteness of his armpits could be seen."
حدثنا محمد بن جعفر حدثنا شعبة قال سمعت أبا إسحاق يحدث أنه
سألت ابن عباس عن قول الرجل بإصبعه يعني هكذا في الصلاة قال ذاك الإخلاص وقال ابن عباس لقد أمرنا رسول الله ﷺ بالسواك حتى ظننا أنه سينزل عليه فيه ولقد رأيت رسول الله ﷺ يسجد حتى يرى بياض إبطيه