Spanish poet of the eleventh century. According to Moses ibn Ezra's treatise on poetry (Neubauer, "Cat. Bodl. Hebr. MSS." No. 1974, fol. 316), his father had emigrated from Africa to Andalusia. Isaac was acquainted with Jacob ibn Jaso, at whose house in Cordova he was a frequent guest (see Abu al-Walid, "Ha-Riḳmah," ed. Goldberg, p. 122; Derenbourg, "Opuscules et Traitésd' Aboû l-Walîd," p. vii.). Abu al-Walid (l.c. p. 186) complains that one of the very few poems that he had written in his early youth had been copied by certain jealous persons and circulated among some people of Toledo with the name of Isaac ibn Ḥalfon as its author; and that when some of his pupils noticed this and asserted Abu al-Walid's authorship, they were disbelieved. Isaac ibn Ḥalfon is quoted as "the poet" ("ha-meshorer") by Moses ibn Ezra in several passages in his above-cited treatise (see Schreiner, "Le Kitab al-Mouhadara," etc., in "R. E. J." xxii. 244). According to Al-Ḥarizi ("Taḥkemoni," xviii., ed. "Aḥiasaf," p. 181, Warsaw, 1899), it seems that Isaac introduced new (perhaps Arabic) meters into Hebrew poetry, which were used by succeeding poets.

Though he doubtless wrote a number of poems, only two may be ascribed to him with any degree of certainty. These are one beginning V06p621003.jpg, metrically translated and published by Michael Sachs, in "Die Religiöse Poesie der Juden in Spanien" (Hebrew part, p. 39; German part, p. 107; comp. also p. 216); and one beginning V06p621004.jpg (see Steinschneider, "Die Handschriften-Verzeichnisse der Königlichen Bibliothek zu Berlin," i. 126, No. 142). If the first-mentioned poem, which has the acrostic V06p621005.jpg, is really genuine, it is probable that V06p621006.jpg is a more correct form of Isaac's name than V06p621007.jpg, though both of them seem to be the Hebrew transliteration of the Arabic "khalfun"(= "banker," "money-changer"). According to Sachs (l.c. p. 289), Isaac ibn Ḥalfon is to be identified with Ḥalfon ha-Levi Abu Sa'id, who lived in Damietta.

That acute critic Al-Ḥarizi (l.c.), in passing judgment upon the value of Isaac's poetry, said that only a few of his poems were beautiful like the fruit of goodly trees (comp. Lev. xxiii. 40), most of them being thorns and thistles. However, among the numerous poets of his age he was "anointed king" (comp. "Taḥkemoni," iii. 39).