Literature Reference: 说尽向来无限事，相看摩捋白髭须。—— 《逢故人》张籍 We spoke of countless past events, while we stroked our white beards. Source from 'Meeting an Old Friend' by Zhang Ji.
摩: Friction, proximity, and mutual refinement.
捋:
Meaning: Stroking white beards symbolizes the passage of time and the depth of friendship.