缘木求鱼（緣木求魚）　

◎ 缘木求鱼 yuánmù-qiúyú

[Do the impossible as one who climb a tree to catch fish—a fruitless approach] 爬上树去找鱼。比喻行事的方向、方法不对,必将劳而无功

今以所重加非其人,望其毗益万分,兴化致理,璧犹缘木求鱼,升山采珠。——《后汉书·刘玄传》