犹yóu豫yù不bù决jué

Literal: hesitate and not decide
Figurative: To keep wavering, going back and forth without making up one's mind; often critical in tone, the opposite of 毫不犹豫.

Where does 犹豫不决 come from?

The phrase goes back to the 《战国策》. When the army of Qin was besieging Handan, the capital of Zhao, the state of Wei sent Xinyuan Yan to propose that Zhao recognize the king of Qin as emperor in exchange for lifting the siege. Lord Pingyuan, Zhao's chief minister, wavered without reaching a decision (犹豫未有所决), until Lu Zhonglian stepped in and talked the envoy out of it. From that line came the fixed form 犹豫不决, used today for any indecision, from choosing an apartment to changing jobs.

Source (出处): 《战国策·赵策三》

How is 犹豫不决 used? Two examples

这zhè两liǎng套tào房fáng子zi各gè有yǒu优yōu点diǎn，我wǒ看kàn了le好hǎo几jǐ遍biàn还hái是shì犹yóu豫yù不bù决jué。
Both apartments have their merits; I've seen them several times and still can't make up my mind.
老lǎo板bǎn对duì这zhè个ge项xiàng目mù一yī直zhí犹yóu豫yù不bù决jué，结jié果guǒ被bèi对duì手shǒu抢qiǎng先xiān了le。
The boss kept wavering over the project, and in the end a competitor beat us to it.

In Wanyu, all 400 chengyu have audio on every sentence, and you can save them to your decks and review them with spaced repetition. Free.