Hadith #5208 (Sunan Abi Dawud)
Book: General Behavior (Kitab Al-Adab)
Narrator(s): Abdul Malik bin Ibrahim al-Jaddi عبد الملك بن إبراهيم الجدي, al-Hasan bin 'Ali al-Halwani الحسن بن علي الخلال الحلواني, Ali ibn Abi Talib, Sa'id bin Khalid al-Khza'y سعيد بن خالد الخزاعي المدني, Ubaidullah bin Abi Rafi' عبيد الله بن أبي رافع
Grade: Hasan Sahih

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.

Source: https://parallelquran.com/hadith/sunan-abi-dawud-5208/