He spoke with him in his language
He spoke with him in the language understood by him or in a manner that enables him to comprehend.
(To a king who sent his son to the land of the sea and he learned the language of the sons of the sea, and when he came from the land of the sea, he began to speak with him in his language. Likewise, since Israel were in the land of Egypt and learned their language, when they came before Mount Sinai, the Holy One, blessed be He, began to distract them with the language 'I am this' - Pesiqta Rabbati (Ish Shalom) section 21 - the Ten Commandments, first portion.)
Translation
Expression (Hebrew)
דִּבֵּר עִמּוֹ בִּלְשׁוֹנוֹ
Definition (Hebrew)
דִּבֵּר אִתּוֹ בְּשָׂפָה הַמּוּבֶנֶת לוֹ אוֹ בְּצוּרָה שֶׁמְּאַפְשֶׁרֶת לוֹ לְהָבִין.
("לְמֶלֶךְ שֶׁשָּׁלַח אֶת בְּנוֹ לִמְדִינַת הַיָּם וְלָמַד לְשׁוֹן בְּנֵי הַיָּם וּכְשֶׁבָּא מִמְּדִינַת הַיָּם הִתְחִיל מְדַבֵּר עִמּוֹ בִּלְשׁוֹנוֹ, כָּךְ לְפִי שֶׁהָיוּ יִשְׂרָאֵל בְּאֶרֶץ מִצְרַיִם וְלָמְדוּ לְשׁוֹנָם כֵּיוָן שֶׁבָּאוּ לִפְנֵי הַר סִינַי הִתְחִיל הקב"ה מֵסִיחַ עִמָּהֶם בִּלְשׁוֹן אָנֹכִי אָנוּךְ"- פְּסִיקְתָּא רַבָּתִי (אִישׁ שָׁלוֹם) פִּיסְקָא כא - י' הַדִּבְּרוֹת פ' קַמַּיְתָא)