Wiktionary
man proposes, god disposes
prov. Things don't always work out as they were planned.
Wikipedia
Man Proposes, God Disposes
Man Proposes, God Disposes is an 1864 oil-on-canvas painting by Edwin Landseer. The work was inspired by the search for Franklin's lost expedition which disappeared in the Arctic after 1845. The painting is in the collection of Royal Holloway, University of London.
Usage examples of "man proposes, god disposes".
But man proposes, God disposes, so let's all hope He knows what He's doing.