2,693. Singling Out the Witnesses

Hilchos Shevuos 9:8

The previous halacha concludes that having testimony must precede taking the oath. With this in mind, let’s say that the plaintiff imposes an oath that the witnesses will testify if they learn anything about him. They answer amen and they later see something relevant. If he insists that they testify and they deny having information, they’re not liable for an oath of testimony.

Hilchos Shevuos 9:9

Witnesses aren’t liable for an oath of testimony unless the plaintiff distinguishes them and imposes an oath, or they take an oath on their own. Accordingly, let’s say that someone stands up in shul and says that he’s imposing an oath that anyone who has testimony about him should testify for him. Everyone says amen, including some actual witnesses. Later, he insists that these witnesses testify and they deny having information. In such a case, they’re not liable for an oath of testimony because he didn’t pick them out of the crowd. But let’s say that he announced, “I impose an oath on everyone standing here that if they have information about me they come testify for me.” Then, if the witnesses are present and they later deny having information, they’re liable for an oath of testimony, because he defined them as the object of the oath along with the others present.