Sayyidina Abu Hurairah (RA) reported on the authority of the Prophet ﷺ that salaam should be offered by the rider to the pedestrian, the pedestrian to the one who is seated, and a fewer number to a larger group. And, Ibn Muthanna added in his hadith: And the young should salute the old. [Ahmed 10630, Bukhari 6231, Muslim 2160, Abu Dawud 5198]