It was only amazement, not envy.
Each person has their own predestined Dharma.
The Heavenly Dao in one's own microcosm was already defying the heavens, even rivaling the achievements of the greater world.
"Benefactor's heritage is also extraordinary, awe-inspiring, and extremely enviable!" Sandu stated candidly.
The breakthrough in his state of mind led him to act on his natural inclinations, hence such remarks.
Sun Wukong slightly lifted his head then burst into laughter and said, "You monk are truly amusing, acting on natural inclinations. It seems you have had some great realization and have now achieved a clear and tranquil mind."
"Amitabha Buddha!"
Sandu nodded his head, a smile also appearing on his lips, and said, "Indeed, I've seen my nature clearly because of the benefactor and have had an epiphany. The timing of every sip and bite is truly wonderful!"
Buddhism emphasizes cause and effect, and every sip and every bite.