Ubada bin Samit reported,

Whenever revelation came down upon the Prophet of Allah ﷺ, he would be overcome with distress and his face would change color.In another narration, whenever revelation came down upon the Prophet ﷺ, he would lower his head, and his companions would lower their heads as well. When the revelation departed from him, he would raise his head.

Azami 6

Sahih

عن عبادة بن الصامت قال

كان نبي الله ﷺ إذا أنزل عليه الوحي كرب لذلك، وتربد وجهه. وفي رواية: كان النبي ﷺ إذا أنزل عليه الوحي نكس رأسه، ونكس أصحابه رؤوسهم. فلما أتلي عنه رفع رأسه.

الأعظمي 6صحيح
Contents
Reference
Commentary
Ayat
Collection
Jami al-Kamil
Book
Revelation
Section
How revelation used to descend upon the Messenger of Allah ﷺ
Numbering
Jami al-Kamil 6 (2nd edition)
Azami 6