These two verses contain four overlapping statements, two positive and two negative.
The repetition is probably for emphasis. It is the writer’s way of bringing home to his readers the fact that there comes a point at which they must choose between the Jewish tradition and the Christian faith (compare Mark 2.12-13; Gal 3.1-18). In some languages it may be more natural and effective to avoid the repetition by shortening or rearranging the text, and this may be possible without loss of meaning.
Our Lord is not expressed in the Greek until verse 14 but is added in verse 13 for clarity. Direct use of the name “Jesus” is avoided in the text, and it should be avoided in translation until it can come in at the climax of verse 21 or 22.
Of whom these things are said probably means “… said in the Old Testament” rather than “of whom we are speaking” (Barclay). This makes a much better parallel to Moses in verse 14. Jerusalem Bible even puts the verb into the past tense, “were said,” to make the Old Testament reference clear, but Hebrews often uses present tenses to show the permanent value of Scripture. Of whom these things are said may be rendered as “about whom there are words in the holy writings,” “about whom the holy writings speak,” or “the holy writings contain these words about him.”
Belonged to is literally “rose” (like the sun); in common language, “came from” (see Luke 1.78; Jer 23.5). Belonged to a different tribe may be rendered as “counted a different person as his forefather” or “did not belong to the people who looked to Levi as their forefather.”
Tribe and its equivalents in some other languages are unacceptable in many parts of the world for describing ethnic groups. Where this is so, some other expression must be found which (a) describes a large kinship group within a nation, (b) has no negative “colonial” overtones, and (c) is not, like “ethnic group,” a technical expression. The situation appears to be rather different in Africa and in some parts of Asia. In Africa, “tribe” and its equivalents in other European languages are widely rejected as implying a condescending attitude to African peoples (as do “native” and similar terms). In parts of Asia, however, members of a dominant ethnic or political group may freely refer, for example, to “hill tribes,” “tribal languages,” and the like. The translator needs to be sure that the expression he uses is fully acceptable to (other) native speakers, whatever their level of education; it is not enough that the term should be commonly applied to them by others. The translator should take into account, not only individual terms, but the way in which they are connected with other words; for example, the noun “a native,” “the natives,” usually has a derogatory meaning in modern English, but it is acceptable for someone to describe himself as “a native of Boston” or to speak of English as his “native language.” At such sensitive points, careful testing of draft translations is particularly important. In choosing a translation for tribe, translators should consider how they would translate the word in such Old Testament passages as Numbers 36.5-9 and Joshua 7.14-18. The expression chosen should refer to a group smaller than a people or nation, but larger than a clan or family.
No member of his tribe ever served as a priest may be expressed as “no one who belonged to the same tribe as our Lord ever served as a priest” or “… was ever a priest.”
It is well known, verse 14, may be expressed as “Everyone knows.”
That he was born a member of the tribe of Judah may be expressed as “our Lord descended from Judah” or “our Lord belonged to the group of people who descended from Judah.”
The importance which the writer gives to what Scripture does not say has already been noted in verse 3. Moses in verse 14 is equivalent to the Torah or Pentateuch. However, did not mention refers to a specific event, either the giving of the Law in general, as in 9.19, or perhaps specifically to the blessing of Levi in Deuteronomy 33.8-11.
Quoted with permission from Ellingworth, Paul and Nida, Eugene A. A Handbook on The Letter of the Hebrews. (UBS Handbook Series). New York: UBS, 1983. For this and other handbooks for translators see here .