He'll never rue but ance, and that'll be a' his life.
"Ride down to Portanferry, and let nae grass grow at the nag's heels; and if ye find him in confinement, ye maun stay beside him night and day for a day or twa, for he'll want friends that hae baith heart and hand; and if ye neglect this, ye'll never rue but ance, for it will be for a' your life."—Guy Mannering.
He'll no gie an inch o' his will for a span o' his thrift.
That is, regardless of expense, his wishes must be gratified.
He'll no gie the head for the washing.
To "keep the head for the washing" is to retain possession of an article which has been made to order or repaired until all charges upon it are paid.
He'll no let the grass grow at his heels.
He'll no sell his hen on a rainy day.
He will not sell his wares at an unpropitious time.
He'll rather turn than burn.