Post: The second pasuk in Bereishit, together with Onkelos, reads:
|א,ב וְהָאָרֶץ, הָיְתָה תֹהוּ וָבֹהוּ, וְחֹשֶׁךְ, עַל-פְּנֵי תְהוֹם; וְרוּחַ אֱלֹהִים, מְרַחֶפֶת עַל-פְּנֵי הַמָּיִם.||וְאַרְעָא, הֲוָת צָדְיָא וְרֵיקָנְיָא, וַחֲשׁוֹכָא, עַל אַפֵּי תְּהוֹמָא; וְרוּחָא מִן קֳדָם יְיָ, מְנַשְּׁבָא עַל אַפֵּי מַיָּא.|
According to Shadal, in Ohev Ger, there is a compelling variant text of Onkelos which has וַחֲשׁוֹכָא פְרִישׂ עַל אַפֵּי תְּהוֹמָא. He writes:
Thus, he ascribes this girsa with פְרִישׂ to Savyonita, Gimel Targumim, and Ch"g. Though in some printings they omit this word (whose meaning is to stretch out). And his mind inclines to preserving it, for had Onkelos not added it (according to the rules of the Aramaic language), the scribes would not have added it on their own, since there is nothing like it in the Hebrew.
Here is an image of the Chumash from Savyonita, 1557. I underlined the word in red.
It is a strong point, and the only possible counter I could come up with is the repeated וְאַפְרֵישׁ (X 2) word and מַפְרֵישׁ (X 1) in close proximity. But that is fairly weak.