(as)

عَلَیْهِ السَّلَام

May peace be upon him

Alayhi salam means 'May peace be upon him,' and is a way of invoking blessings upon the Prophets and the Angels after the mentioning of their blessed names.

This abbreviation is often seen written after the name of any Prophet or Angel is mentioned. Aside from the Holy Prophet Muhammad (sa) - whom is given a higher title of respect after his name, as his name is the Most Honored and Most Revered amongst the Prophets of Time, on whom be peace.