涌泉相报

yǒng quán xiāng bàoyongquanxiangbao

1. to repay a kindness many times over (from the saying 滴水之恩，當湧泉相報|滴水之恩，当涌泉相报[di1 shui3 zhi1 en1 , dang1 yong3 quan2 xiang1 bao4])

Study it in Yanamino