Deuteronomy 4:5-9 (Go to this verse :: Verse pop-up)
Gentiles' observing the results of Israel's obedience to God's law would be drawn to reject their pagan belief system in favor of God's true religion. There is no reference to God's calling these people. Rather, conversion is treated as a fully rational and voluntary choice made when thoughtful pagans recognize the superiority of God's way over their own satanic practices.
In other words, Israel's role was to be an example. God did not command missionary activity on the part of ancient Israel. Israel's proselytism was to be non-verbal, as distinct from the overt verbal action of preaching through the written or spoken word.
Not proselytism through words, but through works, is the God-sanctioned method for ancient Israel. Israel was not so much to preach as it was to obey and to teach. Obeying God's law was an individual responsibility; teaching that law was a parental duty. Notice verse 9, which stresses both roles.
The Old Testament is replete with examples of Gentiles who were won over to Israel by witnessing the unquestioned superiority of God's way of life, and subsequently becoming convinced that His way was for them. One early example may be "Eliezer of Damascus" in Abraham's day, the chief servant in his household. Other examples, certainly, are Ruth in the period of the judges, Uriah the Hittite in David's day and Ebed-Melech in Jeremiah's time. All these quickly come to mind as Gentile converts.
Later on, however, Hellenized Jews caught missionary fever and discarded the approach sanctioned by God. Active—and far-flung—evangelism became the order of the day. Indeed, the first New Testament occurrence of the word proselyte appears in Matthew 23:15 where Christ chastises the scribes' and Pharisees' for their hypocritical approach to spreading their corrupt religion.
Proselytism Yesterday, Today, and Tomorrow (Part One)