Another explanation: “Trust in Hashem forever and ever”: all of a person’s days he must strengthen himself in HaKadosh Baruch Hu (for so David said, “My G-d, I have trusted in You; do not let me be put to shame; do not let my enemies rejoice over me” (Tehillim 25:2)); and whoever places his trust and his strength in Him as is fitting, all the people of the world cannot harm him (for so David said, “My G-d, I have trusted in You; do not let me be put to shame; do not let my enemies rejoice over me”). For whoever places his strength in the holy Name is established in the world. What is the reason? Because the world is established through His holy Name. This is what is written, “for in Kah, Hashem, is the Rock [tzur] of worlds”: He formed [tzayar] the worlds; for with two letters the worlds were created, this world and the World to Come.