Marry in haste, repent at leisure

What's the meaning of the phrase 'Marry in haste, repent at leisure'?

Literal meaning.

What's the origin of the phrase 'Marry in haste, repent at leisure'?

This proverbial saying was first expressed in print by William Congreve in his comedy of manners The Old Batchelour, 1693:

Thus grief still treads upon the heels of pleasure:
Married in haste, we may repent at leisure.

See also: Who wooed in haste, and means to wed at leisure.