One day a mother took her two children with her when she went to color cloth. Not far from her home was a mud hole where the carabao liked to wallow, and to this hole she carried her cloth, some dye pots, and two shell spoons.
After she had put the cloth into the mud to let it take up the dark color, she built a fire and put over it a pot containing water and the leaves used for dyeing. Then she sat down to wait for the water to boil, while the children played near by.
By and by when she went to stir the leaves with a shell spoon, some of the water splashed up and burned her hand, so that she jumped and cried out. This amused the children and their laughter changed them into monkeys, and the spoons became their tails.
The nails of the monkeys are still black, because while they were children they had helped their mother dye the cloth.
How Children Became Monkeys – Philippine Folk Tales