One early non-Jewish source, De Doctrina Christiana (Augustine of Hippo, c. 400 CE) (PDF) Book II, Section 43:
As to the utility of history, moreover, passing over the Greeks, what a great question our own Ambrose has set at rest! For, when the readers and admirers of Plato dared calumniously to assert that our Lord Jesus Christ learnt all those sayings of His, which they are compelled to admire and praise, from the books of Plato — because (they urged) it cannot be denied that Plato lived long before the coming of our Lord! — did not the illustrious bishop, when by his investigations into profane history he had discovered that Plato made a journey into Egypt at the time when Jeremiah the prophet was there, show that it is much more likely that Plato was through Jeremiah's means initiated into our literature, so as to be able to teach and write those views of his which are so justly praised?
For not even Pythagoras himself, from whose successors these men assert Plato learnt theology, lived at a date prior to the books of that Hebrew race, among whom the worship of one God sprang up, and of whom as concerning the flesh our Lord came. And thus, when we reflect upon the dates, it becomes much more probable that those philosophers learnt whatever they said that was good and true from our literature, than that the Lord Jesus Christ learnt from the writings of Plato,—a thing which it is the height of folly to believe.
And a Jewish source, Torat HaOlah by R. Moshe Isserles, c. 1550 CE, Part I Chapter 11:
For in truth, all the wisdom of the philosophers and researchers came from Israel, and all of their wisdom is encompassed in the Torah, as the Rav of the Moreh {Nevuchim?} goes on at length to teach; that all the wisdom of the philosophers is found in the midrashim of Chazal and their aggadot.
And know that I have perused an extremely old sefer and there were sketched in it all the philosophers in their form and their wisdom, how it came about {?}. And it was written in it that Socrates, who is the one that the philosophers call Socrat the Godly, that he was the one who brought out at first in Philosophy that there was a separate reality {?}. And after him were drawn other philosophers. And it is written there that he received the wisdom from Asaf the Korchi {who was in the time of King David} and from Achitofel.
And it is further written in Shevilei Emunah {I think this sefer from R' Meir Ibn Aldabi} that the wisdom of Aristotle was stolen from King Solomon, peace be upon him, for when Alexander the Macedonian conquered Yerushalayim, he set his teacher, Aristotle, to govern over the collection of the books of Solomon.
And every good thing he found in them, he wrote his name upon them, and intermixed in them some of the bad positions, such as the Antiquity of the World and the denial of Providence, in order to cover for himself, so that people who came after him would not know that he stole this wisdom from the Jews.
And it is possible that everything that he did not find a clear-cut proof for in the words of Solomon he did not believe. Regardless, it is explained that all the wisdom are dependent upon the vine {see a similar idea in Ibn Yachya}.
And in truth, it is so that it is fitting for every Jewish person to believe this belief, and not to give our praise and our glory to strangers, the scholars of the nations. And behold, the verses praise Solomon, peace be upon him, that "He spoke of trees, from the cedar that is in Lebanon even to the hyssop that grows on the wall." And if the source of this wisdom was not stolen from him, what was his greatness over Aristotle and those who came after him, who researched into all aspects of nature, as is made clear in their words. Therefore, it is fitting to believe these words, that as we have written, so it is.
(Translation courtesy of R. Josh Waxman. Check out his fascinating blog on the topic.)