Whenever revelation descended upon the Prophet ﷺ, he would lower his head, and his companions would lower their heads as well. Once the revelation had passed from him, he would raise his head.In another narration, whenever revelation descended upon him, he would be overcome with distress and his face would darken.
كان النبي ﷺ إذا أنزل عليه الوحي نكس رأسه، ونكس أصحابه رؤوسهم، فلما أتلي عنه رفع رأسه. وفي رواية: إذا أنزل عليه الوحي كرب لذلك وتربد وجهه.