יָ֘שִׂ֤ישׂוּ וְיִשְׂמְח֨וּ ׀ בְּךָ֗ כָּֽל־מְבַ֫קְשֶׁ֥יךָ יֹאמְר֣וּ תָ֭מִיד יִגְדַּ֣ל יְהוָ֑ה אֹֽ֝הֲבֵ֗י תְּשׁוּעָתֶֽךָ׃
Niech ucieszą i uradują się w Tobie wszyscy pożądający Cię, niech powtarzają wciąż: wielkim jest Bóg, miłujący zbawienie Twoje.
Rabbeinu Bahya
A kabbalistic approach: The words יגדל נא כח א-ד-נ-י mean that the latent power reposing in the attribute of Mercy should be reinforced so that it will not escape into the highest regions of the heavens, [a withdrawal from mankind or the people of Israel of that attribute. Ed.] The whole matter may be understood thus: when the Jewish people perform the commandments and therefore the will of the Lord, G’d will “ride the heavens,” as Moses said in Deut. 33,27 “He rides the heavens with your (Israel’s) help.” Israel’s conduct exerts influence on the manifestation of G’d’s powers. This is the meaning of Psalms 60,14 באלו-הים נעשה חיל, “we will perform valiantly for the sake of the Lord.” On the other hand, when the Jewish people do not observe the commandments He distances Himself from those of His attributes which are invoked often on behalf of Israel. This is the meaning of Deut. 33,29: ובגאותו שחקים, “He will adopt a haughty attitude by withdrawing to the level of the celestial domains known as Shechakim.” In other words, Israel’s sinful conduct causes the manifestations of G’d’s powers to wane. The meaning of the word יגדל in our verse then is that G’d’s powers should become manifest in ever greater measure.
Another reference to the ability of the Jewish people to “weaken” the apparent power of G’d is found in Deut. 32,18 where Moses describes the rebellious Jewish people as causing צור ילדך תשי, “you caused the Rock Who gave birth to you to become ‘weak.’” Seeing that at this point the Israelites had all become guilty of death, Moses was forced to pray that the manifestation of G’d’s power should be great. In Psalms 40,17 David uses a similar language when he concludes with the word יגדל as the word the people who are in search of the Lord are to use when they look for G’d’s help.
Another reference to the ability of the Jewish people to “weaken” the apparent power of G’d is found in Deut. 32,18 where Moses describes the rebellious Jewish people as causing צור ילדך תשי, “you caused the Rock Who gave birth to you to become ‘weak.’” Seeing that at this point the Israelites had all become guilty of death, Moses was forced to pray that the manifestation of G’d’s power should be great. In Psalms 40,17 David uses a similar language when he concludes with the word יגדל as the word the people who are in search of the Lord are to use when they look for G’d’s help.