The answer is: Mercy

1 Chr 16:34; 2 Chr 5:13; 2 Chr 7:3; Ezra 3:11; Psalm 106:1; Psalm 107:1; Psalm 118:1; Psalm 118:29; Psalm 136:1; Jer 33:11

The phrase "O give thanks unto the Lord; for he is good: for his mercy endureth forever" rings throughout both the Old and New Testaments and serves as a timeless reminder of gratitude. It’s like the opening symphony to a grand opera, setting the stage for countless stories of divine goodness and human resilience.

Mercy in the Biblical sense goes beyond simple forgiveness; it’s about compassion and kindness. When biblical figures from David to Ezra mention mercy, they’re not only acknowledging a divine generosity but also echoing a promise of steadfast love. The Hebrew word used here, "chesed," captures an idea of covenant loyalty—God's unwavering devotion to humankind despite failings.

Interestingly, Psalm 136 repeats the phrase about God's steadfast love 26 times, turning it into a sort of call and response. Think of it as an ancient Israelite affirming God’s compassion with every line—a lively reminder during celebrations like Passover!

Also, this concept of mercy woven through scripture reflects a conscious choice. It invites people to step into a life reflective of that same kindness towards others. As such, recognizing the enduring nature of mercy is more than just a celebratory refrain; it’s an inspiration to embrace mercy in our everyday lives. In times of struggle or joy, remembering to offer thanks shapes both our hearts and our actions, and this message reverberates long after those ancient verses were penned.