Assalaamu alaykum. I was sitting behind someone in a conference once, and he put his arm behind himself and his thawb touched my pen. I moved my pen away immediately, but I saw a small ink mark on his clothes, but I did not tell him because we were in the middle of the lesson and I wanted to tell him afterwards. However, I was not able to get the chance in those three days because I either did not see him or I was in the lesson. My question is: is it obligatory upon me to tell him and apologise? Bear in mind that I do see the brother often. What does the Shariah oblige me to do in this case? May Allah reward you.

All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallahu ʻalayhi wa sallam, is His slave and Messenger.

Take it easy upon yourself, dear Brother; there is no need to worry about this matter. Such matters are commonly pardoned among people, and you are not required to tell him about it or apologize to him. The harm that you mentioned is quite insignificant and almost unmentionable. Accordingly, you are not obliged to do anything for this person.

Allah knows best.