I asked Jabir bin Samura, "Did you used to sit with the Messenger of Allah ﷺ?"He replied, "Yes, often. He would not rise from the place where he had prayed the morning prayer until the sun came up, and when the sun rose, he would stand. He would remain silent for long stretches." Abu Nadr said, "He spoke little." The companions would converse, bringing up matters from the days of ignorance and laughing, while he would smile.
حدثنا أبو كامل وأبو النضر قالا ثنا زهير حدثنا
سألت جابر بن سمرة أكنت تجالس رسول الله ﷺ قال نعم كثيرا كان لا يقوم من مصلاه الذي يصلي فيه الصبح حتى تطلع الشمس فإذا طلعت الشمس قام وكان يطيل قال أبو النضر كثير الصمات فيتحدثون فيأخذون في أمر الجاهلية فيضحكون ويتبسم
Its isnad is sahih. It is found in Muslim 1/423, no. 670, in the Book of Prayer, chapter on the merit of sitting in one's place of prayer after the dawn prayer, and in Nasai in the Book of Forgetfulness (Sahw) 2/80, similarly. See also 20706.