Because it is written, Be you holy; for I am holy.
Leviticus 11:44 For I am the LORD your God: you shall therefore sanctify yourselves, and you shall be holy; for I am holy...
Leviticus 19:2 Speak to all the congregation of the children of Israel, and say to them, You shall be holy: for I the LORD your God am holy.
Leviticus 20:7 Sanctify yourselves therefore, and be you holy: for I am the LORD your God.
Amos 3:3 Can two walk together, except they be agreed?