I can even swear by heaven that never do I have the intention not to reply when my mind is clear.

我可以坦然向天发誓，在我清醒的时刻，我绝未存心不回人信。

youdao

I can swear to the heaven, based on Chinese culture, or swear to the God, based on your country's culture, that I neither lie nor overstate.

按照您的国家的文化，我可以对上帝发誓：我绝对没有说谎，也绝对没有夸大。

youdao

Put your hand under my thigh: I want you to swear by the Lord, the God of heaven and earth, that you will not take a wife for my son from the women of the Canaanites in whose land I dwell.

把你的手放在我的大腿下，我要你对天主、对天地的上帝发誓，你不要替我儿子从我居住地的迦南人中娶妻。

youdao