2,694. When the Plaintiff Previously Designated the Witnesses
Hilchos Shevuos 9:10
Let’s say that the plaintiff tells the witnesses to testify for him that person X owes him a maneh (a denomination of currency), after which he gets up in shul and imposes an oath that anyone who has testimony about him should go testify for him. If the witnesses don’t testify, they are liable for an oath of testimony because he already insisted that they testify. This is the case so long as they were in shul when he imposed the oath and the members of a court were also present (because the oath must be imposed in front of a court). In the absence of a court, they are only liable if they answered amen to the oath and denied having information in court; if they didn’t answer amen, they’re exempt.
Hilchos Shevuos 9:11
It makes no difference whether the plaintiff imposes an oath on the witnesses or says “I command you with an oath” or “I bind you with an oath.” In all of these cases, the witnesses are liable so long as the plaintiff imposed the oath using God’s name or one of the phrases used to describe Him as has already been discussed.