From the Han-dynasty
《汉书·董仲舒传》, itself quoting an older proverb:
临渊羡鱼,
不如退而结网 - 'Standing at the deep pool envying the fish is worse than going back and weaving a net.'
董仲舒 used it to urge Emperor Wu of Han to stop admiring ancient peace from afar and instead build the institutions that produce it.