Don’t judge others by yourself.
Tip: This Japanese sentence is a good free translation.
Some of you may wonder how もっと can be written in Kanji. It’s not 持って (to hold/have) but 以て. 以て is 常用外漢字, so もって in Hiragana is more common.
以て means 1) with ways and means; 2) as a result of; 3) at the time when; and 4) until/by (the deadline).
己をもって他人を律するな means “With your own value system, do not control others”. 己をもって is a shortened form of 己の価値観 or 基準をもって.