Qadash means to be holy, consecrate, sanctify, or set apart. It appears about 170 times. It describes the act of making something or someone holy — separating from common use for sacred purposes.
God sanctifies His people, His name, and His dwelling. Israel is called to be holy because God is holy. Sanctification involves both divine action (God sets apart) and human response (consecrating oneself to God). The Sabbath is sanctified, the firstborn are sanctified, priests are sanctified.