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
A titmouse in hands is better than a crane in the sky.
Make a fool pray to God - he will break his forehead.
The forbidden fruit is sweet.
What goes around comes around.
Crowded, but not aggrieved.
Get your sleigh ready in summer and your (horse-drawn) cart in winter.
The eyes are scared, but the hands are doing.
You can't spoil the porridge with butter.