九

Shǔ jiǔ

Counting the nines (a traditional Chinese method of counting the coldest days of winter, starting from the winter solstice).

Dōng liàn sān jiǔ, xià liàn sān fú

Train during the three nines of winter, train during the three dog days of summer (meaning: practice diligently in the harshest conditions).

Jiǔ jìn hán jìn.

When the nine periods end, the cold ends (meaning: after the coldest period of winter passes, spring arrives).