The Prophet ﷺ said: When one of you comes to an assembly, he should give a salutation and if he feels inclined to get up, he should give a salutation, for the former is not more of a duty than the latter. (Using translation from Abū Dāʾūd 5208)
قَالَ رَسُولُ اللهِ ﷺ إِذَا أَتَى أَحَدُكُمُ الْمَجْلِسَ فَلْيُسَلِّمْ فَإِنْ بَدَا لَهُ أَنْ يَقْعُدَ فَلْيُسَلِّمْ إِذَا قَامَ فَلَيْسَتِ الْأُولَى بِأَوْجَبَ مِنَ الْآخِرَةِ