Exodus 28:28

וירכסו — This is an expression for joining. Similar in meaning is, (Psalms 31:21) “[Thou hidest them] from the רֻכְסַי of men”, i. e. from the union of companies of wicked people. Similar is, (Isaiah 40:4) “And the רכסים shall become a plain” — i. e. the mountains which are close (almost joined) to one another so that it is not possible to descend into the valley between them except with great difficulty, since, in consequence of their closeness to each other, the valley is precipitous and deep — these רכסים, connected mountains, shall become a level plain and easy to travel upon. להיות על חשב האפוד THAT IT MAY BE UPON THE GIRDLE OF THE EPHOD — that the breast-plate (not the ring) may be attached to the girdle of the ephod. ולא יזח SO THAT [THE BREAST-PLATE] BE NOT LOOSENED — יזח is an expression for “breaking away”. It is an Arabic expression according to the opinion of Dunash ben Labrat.

וְיִרְכְּס֣וּ אֶת־הַ֠חֹ֠שֶׁן מִֽטַּבְּעֹתָ֞ו אֶל־טַבְּעֹ֤ת הָאֵפוֹד֙ בִּפְתִ֣יל תְּכֵ֔לֶת לִֽהְי֖וֹת עַל־חֵ֣שֶׁב הָאֵפ֑וֹד וְלֹֽא־יִזַּ֣ח הַחֹ֔שֶׁן מֵעַ֖ל הָאֵפֽוֹד׃

And they shall bind the breastplate by its rings to the rings of the efod with a lace of blue, that it may be above the finely wrought girdle of the efod, and that the breastplate be not loosed from the efod.