功德无量 immeasurable merit
Explanation
功德：功业和德行；无量：无法计算。旧时指功劳恩德非常大。现多用来称赞做了好事。
Merit and virtue; immeasurable. It formerly referred to great merit and benevolence. Now, it's mostly used to praise someone for doing good deeds.
Origin Story
汉武帝时期，丙吉担任廷尉，他正直廉洁，为官清正，深受百姓爱戴。一次，汉武帝要诛杀所有犯人，其中就包括汉宣帝的亲属。丙吉冒着巨大的风险，保护了汉宣帝的亲属，使他们免遭杀害。后来汉宣帝即位后，对丙吉的恩情一直铭记于心，认为他功德无量。
During the reign of Emperor Wu of the Han Dynasty, Bing Ji served as a high-ranking official. Known for his integrity and fairness, he was deeply respected by the people. On one occasion, Emperor Wu ordered the execution of all prisoners, including relatives of the future Emperor Xuan. Bing Ji, at great personal risk, secretly protected Emperor Xuan's relatives, saving them from death. Later, when Emperor Xuan ascended the throne, he always remembered Bing Ji's kindness and considered his merits immeasurable.
Usage
用于赞扬做了好事的人或事，表达其功劳和恩德非常大。
Used to praise a person or thing that has done good deeds, expressing that their merit and benevolence are very great.
Examples
-
他为国家做出了巨大贡献，功德无量。
tā wèi guójiā zuò chū le jùdà gòngxiàn, gōng dé wú liàng.
He made a great contribution to the country; his merits are immeasurable.
-
为了帮助他人，他默默奉献，功德无量。
wèile bāngzhù tārén, tā mòmò fèngxiàn, gōng dé wú liàng.
To help others, he silently dedicated himself; his merit is immeasurable.