のだから (no da kara)

Related patterns5

since it is the case that — a shared reason nobody can deny

まだ子供こどもなんだから、そんなに怒おこらなくてもいいじゃない。
mada kodomo nan da kara, sonna ni okoranakute mo ii ja nai.
He's still a child, so there's no need to get that angry with him. casual
せっかく遠とおくまで来きたのだから、もう少すこしゆっくり見みていこう。
sekkaku tooku made kita no da kara, mou sukoshi yukkuri mite ikou.
We've come all this way, so let's take a bit longer to look around. neutral
一度いちど引ひき受うけると言いったんですから、最後さいごまでやってください。
ichido hikiukeru to itta n desu kara, saigo made yatte kudasai.
You did say you would take it on, so please see it through to the end. neutral
皆様みなさまにお集あつまりいただいたのですから、忌憚きたんのないご意見いけんをお聞きかせください。
minasama ni oatsumari itadaita no desu kara, kitan no nai go iken o okikase kudasai.
Since you have all taken the trouble to gather here, please give us your frank opinions. formal

んだからndakaracolloquial
味あじわうんだから
the spoken squeeze, and the one that carries reproach — 言いったんだから、ちゃんとやってよ presses the hearer with something they cannot deny.

The main sentence must be a verdict, a request, or an order. A plain event report doesn't fit here; から covers that instead.