ה֤וֹי כָּל־צָמֵא֙ לְכ֣וּ לַמַּ֔יִם וַאֲשֶׁ֥ר אֵֽין־ל֖וֹ כָּ֑סֶף לְכ֤וּ שִׁבְרוּ֙ וֶֽאֱכֹ֔לוּ וּלְכ֣וּ שִׁבְר֗וּ בְּלוֹא־כֶ֛סֶף וּבְל֥וֹא מְחִ֖יר יַ֥יִן וְחָלָֽב׃
Ho, every one that thirsteth, come ye for water, And he that hath no money; Come ye, buy, and eat; Yea, come, buy wine and milk Without money and without price.
Rashi on Isaiah
Ho! All who thirst Heb. הוֹי. This word הוֹי is an expression of calling, inviting, and gathering, and there are many in Scripture, [e.g.,] (Zech. 2:10) “Ho! Ho! and flee from the north land.”
Ibn Ezra on Isaiah
הוי Ho ! It is the sign of the vocative. Ho, every one that thirsteth, etc. With these words the Lord will address those who will then be desirous to accept the Law.