This was Laurence Olivier's second and film appearance in a Shakespearean theatrical film which he did not direct himself. The first was As You Like It (1936), in which he played Orlando.
Othello: I pray you, in your letters; when you shall these unlucky deeds relate, speak of them as they are. Nothing extenuate, nor set down aught in malice. Then must you speak of one that lov'd not wisely but too well.