How about "徐かなること林の如く"?
It is originally a quote from Sun Tzu's The Art of War (故其疾如風、其徐如林、侵掠如火、難知如陰、不動如山、動如雷霆。), which was later adopted and popularized in Japan by Takeda Shingen who used the line "疾きこと風の如く、徐かなること林の如く、侵略すること火の如く、動かざること山の如し", commonly referred to as "風林火山", on his battle flags.
