זוהר בראשית — דף קיו ע”א

“Your children like olive shoots” are Israel in the land, eating, offering sacrifices and rejoicing before the Holy One, blessed be He. After the Divine Presence departed and Israel went into exile from their father’s table, they cry out among the nations, and many holy ones died in harsh decrees, as a punishment for the Torah they had not kept. The verse “because you did not serve the Lord your God with joy and gladness of heart, out of the abundance of all things” is explained: joy is the priests and the sacrifices; gladness of heart, the Levites; abundance of all things, Israel, who stood in the middle. “You have multiplied the nation” refers to Israel, “you have increased the joy” to Abraham’s degree, and “as with joy at harvest” to Knesset Yisrael.