放……一马。(Fàng ……yì mǎ.)let somebody off the hook; to make it easy on somebody later.

Explanation

三国时期，关羽为报恩，放走战败的曹操。“放……（某人）一马”后来指对某人手下留情。
In the period of three kingdoms, Guan Yu released Cao Cao to pay Cao’s obligation. Later, “放……（某人）一马”means to show mercy on somebody.

Words:

毕竟bìjìnɡ:after all;
开除kāichú:fire.

Sentences

1、Jiǎ: Yěxǔ wǒ yīnggāi fàng tā yì mǎ.
甲：也许我应该放他一马。
A: Maybe I should let him off.

Yǐ: Shì a, bìjìng tā bāngzhù guò wǒmen.
乙：是啊，毕竟他帮助过我们。
Bi: I agree. After all, he had helped us.

2、Jiǎ: Lǎobǎn fàng le wǒ yì mǎ, méiyǒu kāichú wǒ.
甲：老板放了我一马，没有开除我。
A: The boss took it easy on me and did not fire me.

Yǐ: Nǐ yǐhòu yào nǔlì gōngzuò bàodá tā.
乙：你以后要努力工作报答他。
B: You should work harder to repay him.

原文链接