Sayyiduna Ibn Umar (may Allah be pleased with them both) used to dye his clothes with saffron and also apply saffron as oil. When he was asked why he dyed his clothes with saffron and used saffron as oil, he said: The reason is that I have seen that among all colors, the most beloved color to the Noble Prophet (peace and blessings be upon him) was saffron, which he (peace and blessings be upon him) used to apply to his clothes and also use as oil.
Hadith Referenceالفتح الربانی / كتاب اللباس والزينة / 7932
Benefits: … By "using it as oil," it is meant that the Prophet sallallahu alayhi wa sallam would dye his hair with it. In the narration of Abu Dawud, it is clarified that the Prophet sallallahu alayhi wa sallam would dye his blessed beard with it.