Padoko padoko, hapadzokeri pakare.

What has been done, even if slowly, will not become undone.

What it means
Work done slowly is still work done, and it stays done. The proverb says that slow progress is progress all the same.
Shona · Southern Africa
Source and context
From: Shona, Southern Africa
Source: Shona (Zimbabwe) proverb (tsumo); original text, translation and explanation from "Tsumo: 20 Shona proverbs to inspire good work habits," ZimbOriginal (zimboriginal.com).

The source explains it: slow progress is still progress. The wording of the meaning is ours.