2,721. When a Minor Makes an Oath

Hilchos Shevuos 12:6

If a servant takes an oath, his master need not make him violate the oath. Rather, the servant is exactly the same as he was before he made the oath. This is because his body is not his own for the oath to be effective. Numbers 30:3 tells us that an oath is “to prohibit something upon one's soul.” This only applies to one whose soul is his own, excluding a servant who is his master’s. A servant taking an oath is tantamount to taking an oath about someone else’s property, which is ineffective.

Hilchos Shevuos 12:7

Minors who make oaths aren’t required to uphold them even if they understand the ramifications of an oath. Despite this, we make them keep their word to teach them and to keep them from treating oaths lightly. If the subject of the oath is something that a minor couldn’t fulfill without harm, such as if he made an oath to fast or not to eat meat for a long time, his father or his teacher should chastise him to make it look as if the oath effective but absolved. This is to teach the child not to treat oaths lightly.