William Burkitt on 2 Timothy 4:19

Observe here, How mindful the apostle is of his absent friends; though he was now in prison, and they a great way from him, yet he sends pious salutations to them. This Prisca or Priscilla, and Aquilla, are often remembered by St. Paul, he lodged in their house at Corinth: The saints and servants of God forget not one another, when at the ends of the earth. - He salutes also Onesiphorus and his household, wife and children, and servants. Thus do pious governors procure a blessing upon their families as well as upon their persons. Onesiphorus is not only prayed for himself, and saluted singly, but likewise his household also; Salute Prisca and Aquilla, and the household of Onesiphorus.