He had married in 1701 Joanna, daughter of Sir John Bernard of Brampton in Huntingdonshire. Their union lasted forty years. Mrs Bentley died in 1740, leaving a son, Richard, and two daughters, one of whom married in 1728 Mr Denison Cumberland, grandson of Richard Cumberland, bishop of Peterborough. Their son was Richard Cumberland, the dramatist. Surrounded by his grandchildren, Dr Bentley experienced the joint pressure of age and infirmity as lightly as is consistent with the lot of humanity. He continued to amuse himself with reading; and though nearly confined to his arm-chair, was able to enjoy the society of his friends and several rising scholars, J. Markland, John Taylor, his nephews Richard and Thomas Bentley, with whom he discussed classical subjects. He was accustomed to say that he should live to be eighty, adding that a life of that duration was long enough to read everything worth reading. He fulfilled his own prediction, dying of pleurisy on the 14th of July 1742. Though accused by his enemies of being grasping, he left not more than £5000 behind him. A few Greek MSS., brought from Mount Athos, he left to the college library; his books and papers to his nephew, Richard Bentley. Richard, who was a fellow of Trinity, at his death in 1786 left the papers to the college library. The books, containing in many cases valuable manuscript notes, were purchased by the British Museum.
Of his personal habits some anecdotes are related by his grandson, Richard Cumberland, in vol. i. of his _Memoirs_ (1807). The hat of formidable dimensions, which he always wore during reading to shade his eyes, and his preference of port to claret (which he said "would be port if it could") are traits embodied in Pope's caricature (_Dunciad_, b. 4), which bears in other respects little resemblance to the original. He did not take up the habit of smoking till he was seventy. He held the archdeaconry of Ely with two livings, but never obtained higher preference in the church. He was offered the (then poor) bishopric of Bristol but refused it, and being asked what preferment he would consider worth his acceptance, replied, "That which would leave him no reason to wish for a removal."