Deuteronomy 22:15

22:15 Then the father and mother of the young woman must produce the evidence of virginity ¹  for the elders of the city at the gate.

[22:15]  ¹ sn In light of v. 17 this would evidently be blood-stained sheets indicative of the first instance of intercourse. See E. H. Merrill, Deuteronomy (NAC), 302-3.