With accent marks:
Долг платежо́м кра́сен.
The beauty of a debt is its payment
This proverb reminds us that we should always pay our debts back.
The word красен here comes from красный (red). In the old times, красный meant красивый.
The closest English equivalent is "One good turn deserves another".
Other Russian proverbs
Strike the iron while it's hot.
A bad example is contagious.
The demon is not as scary as he is depicted.
Live for a century, learn for a century, but die being a fool anyway.
(lit.) Whoever gets up early, God gives him
Time for business, an hour for fun.
Each sandpiper praises its swamp.
Not everything that glitters is gold.