A proverb meaning someone keeps their word and does not go back on what they have said. Historically praises a man's reliability, but in modern use can be applied regardless of gender.
約束した以上、男に二言はない。必ず明日までに仕上げる。
Since I promised, a man's word is his bond. I'll definitely finish it by tomorrow.
彼は昔から『男に二言はない』と言って、頼まれたことは必ずやる人だ。
He has always said 'a man's word is his bond' and always does what he's asked to do.
このことわざは性別観に基づいた表現だと批判されることもあるが、要するに『言ったことは守る』という意味だ。
This proverb is sometimes criticized for its gendered view, but essentially it means 'keep your promises.'