ちかchikau
1.

To firmly commit oneself to performing a specific action, often in the presence of a deity or for the sake of a significant promise.

2.

To make a solemn promise that involves a serious commitment, typically associated with the understanding that breaking this promise may incur consequences.

3.

To declare one's intent or desire in a binding manner, especially in the context of relationships or future plans, indicating a mutual agreement to uphold a shared commitment.

Example:

君は聖書に手をのせて誓うべきだ。