一いち夜やを共ともにする

expression, suru verb (irregular)

spend a night together

Often implies sharing a bed or having a sexual encounter, but can also refer to simply staying overnight together in a non-sexual context depending on the situation.

• 彼かれらは旅たび先さきで一いち夜やを共ともにした。

  They spent a night together on their trip.