Premanand Maharaj Ji
Is standing on the side of adharma also a sin, even if I don't do the wrong myself?
Siding with adharma brings its fruit
Bhishma knew fully that the side opposing Yudhishthira was on adharma (wrong, unrighteous action), yet he stayed on it and lay six months on a bed of arrows. Drona was also on the side of adharma and was cut down. Adharma is like sowing babool: you get only thorns.
They were on the side of adharma. It is not necessary that you yourself do wrong; adharma, by anyone, anywhere, in any way, is like sowing a babool tree: it will bear only thorns.