introite in conspectu ejus --- why abl. ?

[Junya]

Hi.

introite in conspectu ejus
in exsultatione

This is from one of Gregorian chants. (Psalm 100 in Vulgata ?)
My question is on in conspectu.
This should mean in conspectum.
In medieval Latin is this confusion of ablative and accusative before prepositions rare or common ?

[adrianus]

I understand what you mean. I think it's not a confusion:
Te intellego. Ut opinor id non confusum est nec soloecismus:
"Introite in conspectu ejus in exultatione" = "[When] before him/in his presence, enter with joy."
and not // non "Enter his sight in joy" ("Introite in conspectum ejus in exultatione.")

[Junya]

Hi.
Thank you.
I'll check the place again, and
if in conspectu is still a problem then, let me post a question again to you.