שַׁבַּח קֳדָם יְיָ וְשֵׁזְבֵיהּ פְּצָא יָתֵיהּ מְטוּל דְאִתְרְעֵי בֵיהּ.
1. One who casts himself | גֹּל – The word "גֹּל" stems from the root "גלל", to roll, with the connotation being that the one who turns to God, trusting in Him to care for him, will be saved (see Rashi, Ibn Ezra and Radak, and compare our verse to the similar "גּוֹל עַל י"י דַּרְכֶּךָ וּבְטַח עָלָיו וְהוּא יַעֲשֶׂה" in Tehillim 37:5).In response to the mocking of his enemies, the psalmist reminds himself (and others) that those who turn to God will find deliverance. Alternatively, the whole verse comprises the words of the enemy, who mock: "let him cast himself upon Hashem; let Him rescue him (or perhaps: "will He rescue him?") (Sforno, Malbim) Such words would have played into the psalmist's own doubts as he himself questions why God has abandoned him.
2. He delights in him | כִּי חָפֵץ בּוֹ – The translation assumes that the subject of the sentence is God and the object is those who trust in Him (compare Bemidbar 14:8) Alternatively, the subject of the clause is the one who trusts in Hashem and the object is Hashem (see Ibn Ezra and Radak for both options).