Abu Uthman An-Nahdi (At-Taabi'ee) radiyallahu anhu relates that Rasoolullah sallallahu alaihe wasallam said:
If one is given rayhaan, he should not refuse it, because it originates from Jannah (IT)
English reference (IT): Book 32, Hadith 211 (IT)
Arabic reference (IT): Book 33, Hadith 221 (IT)