“Of whom (it) hath been spoken”
This referential phraseology occurs twice in the Book of Mormon.
Currently there are eight other instances known: 1550–1710.
3 Nephi 26:14
And it came to pass that he did teach and minister
unto the children of the multitude, of whom hath been spoken,
and he did loose their tongues.
1550,
purchased to cause hym to be adiournedde or somoned in Sycile,
togiders w
1583,
seruing their owne turnes with all practises and cheuisaun
c1600, Google Books, 33 • Google Books, 439
The book lying in her window,
her maid (of whom hath been spoken) took it up,
1649,
the most of these Heads no doubt were of the great Sanhedrim, and though in the affairs of the Temple the Sagan, Katholikin, Immercalin and Gizbarin, of whom hath been spoken already, were above them;
1657,
in the same hill where the Iron-mine was of Mr. Christopher Wandsworth, of whom hath been spoken above.
Alma 5:21
yea, his garments must be purified until it is cleansed from all stain
through the blood of him of whom it hath been spoken by our fathers
which should come to redeem his people from their sins.
1563,
The begynnynge of Rome was at that tyme as the Kynge Salmanasar (of whome it hath been spoken) dyd raygne ouer the Assyrians.
1580,
for they cannot hide themselues so wel, but they wil be surprised:
but hee speaketh of them of whome it hath bene spoken off heretofore.
1710, Google Books, 156
And that will belong to him far more than to some of whom it hath been spoken;
This is the one example of the phrase “did teach and minister” that I found outside of the Book of Mormon:
1590,
P. Martyr saith, there were two sorts of Elders: the one which did teach and minister the Sacraments, and did gouerne with the Bishops:
Here is an early modern example of the pronoun it referring back to garments:
1619,
when the Souldiers that executed him, parted his garments among them,
and to saue it from quartering, cast Lots apart vpon one of them,