Bismillaah:

Simaak ibn Harb رضي اللّه عنه said:

“I said to Jaabir ibn Samurah, '' Were you used to sit with the Prophet صلي الله عليه وسلم ?' He replied, 'Yes, often. He used to not get up from his place where he had prayed the Fajr prayer until the sun would rise, and when the sun would rise, then he would get up, and the companions would recall the stories of the pre-Islamic era of ignorance and they would laugh, and the Prophet would smile.'”

Takhreej:

{ Imam Muslim in his Saheeh }

Imam An Nawaawi رحمه الله commented:

“This is evidence that it is desirable to mention Allaah after the Fajr prayer and to sit where one has prayed the Fajr prayer unless one has a sound reason to leave.”

{ Al Minhaj Sharh Saheeh Muslim }

Imam Qadhi Iyaad رحمه الله commented:

“This is a Sunnah which the Salaf and the scholars used to do.”

{ Sharh Saheeh Muslim }

This hadeeth also points to the fact that there is nothing wrong in discussing worldly matters in the Masjid, however it should be moderate in order to accommodate others worshiping Allaah عزوجل .

*** And Allaah عزوجل knows best ***