The kindness of a drop of water is repaid by a spring of water

Virtue is important and kindness is as great as a mountain. Gratitude is the smallest of virtues, and ingratitude is the worst of vices. - British proverb

The kindness of parents cannot be drowned in water or extinguished by fire. -Soviet proverb

If you are not a family member, you will not know how valuable firewood and rice are: If you do not raise children, you will not be able to repay your mother's kindness. -Chinese proverb

Whoever speaks with an inch of grass will be rewarded with three rays of spring.