I used to come to the Prophet ﷺ while he was praying, and I would greet him with the salam, and he would return my greeting. Then I came to him once and greeted him while he was praying, but he did not return my greeting. When he finished, he gestured to the people and said, "Allah has now ordained concerning the prayer that you are not to speak during it except with the remembrance of Allah and what is fitting for you, and that you stand before Allah in devout obedience."
أخبرنا محمد بن عبد الله بن عمار قال حدثنا ابن أبي غنية واسمه يحيى بن عبد الملك والقاسم بن يزيد الجرمي عن سفيان عن الزبير بن عدي عن كلثوم
كنت آتي النبي ﷺ وهو يصلي فأسلم عليه فيرد علي فأتيته فسلمت عليه وهو يصلي فلم يرد علي فلما سلم أشار إلى القوم فقال إن الله عز وجل يعني أحدث في الصلاة أن لا تكلموا إلا بذكر الله وما ينبغي لكم وأن تقوموا لله قانتين
[hasan] It is also in al-Kubra, no. 558, and from this route Ibn Abdul-Barr narrated it in al-Tamhid, 1/355, and the hadith has many corroborating narrations.Sufyan Thawri narrated with an "an" formula from Kulthum, who is Ibn Alqama bin Najiya bin Mustaliq Khuzai, a trustworthy narrator who is said to have had companionship with the Prophet.