Alcuin of York (735-804) wrote in 797 to Higbald, Bishop of Lindisfarne, about the introduction of secular music and the harp (cithara) into the cloisters. Alcuini Epistulae, ed. Dümmler, (Mon. Germ. Hist., Epist. Karolini Aevi, ii), pp. 181 ff., quote on p. 183:
verba Dei legantur in sacerdotali convivio. Ibi decet lectorem audiri, non citharistam; sermones patrum, non carmina gentilium. Quid Hinieldus cum Christo?
Ingeld is mentioned at Beowulf 2020-2069 and Saxo Grammaticus 6.182 ff.
(From this page, 10.15.02)