Giobbe 16:19

Also now, behold, my witness [is] in heaven, and my record [is] on high.

Ver. 19. Also now behold my witness is in heaven] Here is his appeal to God. So great is the confidence of a good conscience. We also may do the like, if there be no other way left for clearing our innocence; provided that we do it with a clear conscience, and in a matter of consequence; not in jest, but in judgment. Some of the martyrs appealed thus, and cited their persecutors to answer at God's tribunal.

Yea, to help the truth in necessity, a private oath between two or more may be lawfully taken, so it be done sparingly and warily; for in serious affairs and matters of great importance, if it be lawful in private to admit God as a judge, why should he not as well be called to witness? Again, the examples of holy men show the practice of private oaths as not unlawful. Jacob and Laban confirmed their covenant by a private oath, so did Jonathan and David, &c.