发誓 (fā shì): เพื่อสาบาน

On their wedding day, they vowed in front of relatives and friends to love each other for a lifetime, and to stay together through poverty and wealth.

He vowed never to lie again, but the next day when his mom asked if he had finished his homework, he lied again.

The police officer asked him to vow to tell the truth; he raised his right hand and promised that every word he said would be true.

I vow to you that I will call you every day from now on, and I won't leave you waiting alone anymore.