*Minor differences ignored. Grouped by changes, with first version listed as example.
But when he shall have turned to the Lord. This passage has hitherto been badly rendered, for both Greek and Latin writers have thought that the word Israel was to be understood, whereas Paul is speaking of Moses. He had said, that a veil is upon the hearts of the Jews, when Moses is read. He immediately adds, As soon as he will have turned to the Lord, the veil will be taken away. Who does not see, that this is said of Moses, that is, of the law? For as Christ is the end  of it, (Romans 10:4,) to which it ought to be referred, it was turned away in another direction, when the Jews shut out Christ from it. Hence, as in the law  they wander into by-paths, so the law, too, becomes to them involved like a labyrinth, until it is brought to refer to its end, that is, Christ. If, accordingly, the Jews seek Christ in the law, the truth of God will be distinctly seen by them,  but so long as they think to be wise without Christ, they will wander in darkness, and will never arrive at a right understanding of the law. Now what is said of the law applies to all Scripture -- that where it is not taken as referring to Christ as its one aim, it is mistakingly twisted and perverted. 
1 - "La fin et l'accomplissement d'icelle;" -- "The end and accomplishment of it."
2 - "En lisant la Loy;" -- "In reading the Law."
3 - "Ils y trouuerout clairement la pure verité de Dieu;" -- "They will clearly discover in it the pure truth of God."
4 - "C'est la destourner hops de son droit sens et du tout la peruertir;" -- "This is to turn it away from its right meaning, and altogether to pervert it."
Nevertheless - This is not always to continue. The time is coming when they shall understand their own Scriptures, and see their true beauty.
When it shall turn to the Lord - When the Jewish people shall be converted. The word "it" here refers undoubtedly to "Israel" in 2-Corinthians 3:13; and the sense is, that their blindness is not always to remain; there is to be a period when they shall turn to God, and shall understand his promises, and become acquainted with the true nature of their own religion. This subject the apostle has discussed at much greater length in the eleventh chapter of the Epistle to the Romans; see the notes on that chapter.
The vail shall be taken away - They shall then understand the true meaning of the prophecies, and the true nature of their own institutions. They shall see that they refer to the Lord Jesus, the incarnate Son of God, and the true Messiah. The genuine sense of their sacred oracles shall break upon their view with full and irresistible light. There may be an allusion in the language here to the declaration in Isaiah 25:7, "And he will destroy in this mountain the face of the covering cast over all people, and the vail that is spread over all nations." This verse teaches:
(1) That the time will come when the Jews shall be converted to Christianity; expressed here by their turning unto the Lord, that is, the Lord Jesus; see the note, Acts 1:24.
(2) it seems to be implied that their conversion will be a conversion of "the people" at large; a conversion that shall be nearly simultaneous; a conversion "en masse." Such a conversion we have reason to anticipate of the Jewish nation.
(3) the effect of this will be to make them acquainted with the true sense of their own Scriptures, and the light and beauty of the sayings of their own prophets, Now they are in deep darkness on the sub ject; then they will see how entirely they meet and harmonize in the Lord Jesus.
(4) the true and only way of having a correct and full meaning of the Bible is by turning unto God. Love to Him, and a disposition to do His will, is the best means of interpreting the Bible.
When it shall turn to the Lord - When the Israelitish nation shall turn to the Lord Jesus, the veil shall be taken away; the true light shall shine; and they shall see all things clearly.
There is an evident allusion here to the case of Moses, mentioned Exodus 34:34. When he came from the Lord, and spoke to the Israelites, he put the veil over his face; but when he returned to speak with the Lord, then he took off the veil. So, when the Israelitish nation shall return to speak with and pray to the Lord Jesus, the veil of darkness and ignorance shall be taken away from their hearts; but never before that time. The words seem to imply:
1. That there will be a conversion of the Jews to Christianity; and,
2. That this conversion will be en masse; that a time will come when the whole nation of the Jews, in every place, shall turn to Christ; and then the Gentiles and Jews make one fold, under one Shepherd and Bishop of all souls.
Nevertheless, when it shall turn to the Lord,.... The heart, upon which the veil now is; or the body of the Jewish nation, as in the latter day; when they "shall turn", or "be turned", by the Spirit, power, and grace of God, to the Lord Jesus Christ, and look upon him whom they have pierced, and mourn, and embrace him as the true Messiah and only Saviour:
the veil shall be taken away; the veil of blindness and ignorance, respecting themselves, case, state, and condition, and the way of salvation by Christ; the veil of unbelief, with regard to his person, offices, and grace, and of error in points of the greatest moment and importance; then all the darkness and obscurity that is upon the books of Moses and the prophets, and which is now upon their hearts in reading them, will be gone. The prophecies of the Old Testament will be seen in their proper light, and to be evidently fulfilled in Christ; the true nature, use, and end of the law, will be discovered; and both they and that will be freed from all darkness that now attends them. The Jews themselves acknowledge, that though the law is light, yet there is an obscurity in it, by reason of the several ways of interpreting it; and therefore,
"he that studies in it, has need to remove, , "veil after veil", which is upon the face of it, in order to come at the light of it (g):''
and intimate, that the veil on Moses's face was an emblem of this obscurity, which agrees with what the apostle hints in this context; and also own, that there is now upon them a veil of ignorance; and, say they (h), God has promised to remove, , perhaps it should be "the veil of folly off of our understanding", referring, as is thought, to Isaiah 25:7.
(g) R. Abraham Seba in Tzeror Hammor, fol. 90. 2. (h) Chobat Halebabot, par. 1. c. 3. apud L. Capell. in loc.
Moses took off the veil on entering into the presence of the Lord. So as to the Israelites whom Moses represents, "whensoever their heart (it) turns (not as English Version, 'shall turn') to the Lord, the veil is (by the very fact; not as English Version, 'shall be') taken away." Exodus 34:34 is the allusion; not Exodus 34:30-31, as ALFORD thinks. Whenever the Israelites turn to the Lord, who is the Spirit of the law, the veil is taken off their hearts in the presence of the Lord: as the literal veil was taken off by Moses in going before God: no longer resting on the dead letter, the veil, they by the Spirit commune with God and with the inner spirit of the Mosaic covenant (which answers to the glory of Moses' face unveiled in God's presence).
When it - Their heart. Shall turn to the Lord - To Christ, by living faith. The veil is taken away - That very moment; and they see, with the utmost clearness, how all the types and prophecies of the law are fully accomplished in him.
*More commentary available at chapter level.