Bede's Ecclesiastical History of England, ed. by A.M. Sellar, [1907]
AT this time, King Oswy was exposed to the cruel and intolerable invasions of Penda, king of the Mercians, whom we have so often mentioned, and who had slain his brother; at length, compelled by his necessity, he promised to give him countless gifts and royal marks of honour greater than can be believed, to purchase peace; provided that he would return home, and cease to waste and utterly destroy the provinces of his kingdom.