Such references are found (cryptically) in Greek authors including the pre-Socratics and Herodotus, and (more explicitly) in Ecclesiastes 5:3 and Ecclesiasticus 34:1-7.
Throughout his life he corresponded with continental scholars, by whom he was much esteemed, as evidenced by Gronovius's dedication to Ellys of his edition of Ælian's Varia Historia, and the Wetsteins' edition of Johann Caspar Suicer's Thesaurus Ecclesiasticus, to which he had contributed the use of a manuscript.