Umar bin Hafs bin Ghyath عمر بن حفص بن غياث · Chapters on Seeking Permission

from Abu Hurairah that the Prophet (ﷺ) said: "The rider gives the Salam to the walking person, and the walking person to the sitting person and the few to the many." Ibn Al-Muthanna added in his narration: "And the young one gives the Salam to the elder."