Matthew Poole and continuators on John 5:39

39 Search the Scriptures , for in them ye think ye have eternal life , and they are they which testifie of me .

The words may be read either Imperatively (as our Translation readeth them) or Indicatively; you do search the Scriptures (that is, of the Old Testament, for the Books of the New Testament were not at that time written) but as they had the Books of the Old Testament, so they made use of them: Moses was read in the Synagogues every Sabbath-day; and they (the Pharisees especially) were very well versed both in the Law and the Prophets:

They did agree that the way of Salvation and Everlasting Life was revealed unto them in the Holy Scriptures; nay, they did judge, that Eternal Life was to be obtained by their observation of the Law

They (saith our Saviour) are my principal Testimony; he doth not onely say, they testifie, but they are they that testifie. No Writings but those testifie of me; I principally appeal to them to give you an account of me.

Marginal references: Isa. 8.20. and 34.16. Luke 16.29. Acts 17.11.; Deut. 18.15, 18. Luke 24.27. Chap. 1.45.