WSC Q.61: What is forbidden in the fourth commandment?
The fourth commandment forbiddeth the omission or careless performance of the duties required, (Amos 8:5, Mal. 1:13) and the profaning the day by idleness, (Acts 20:7,9) or doing that which is in itself sinful, (Ezek. 23:38) or by unnecessary thoughts, words, or works, about our worldly employments or recreations. (Jer. 17:24–26, Isa. 58:13)
WLC Q.119: What are the sins forbidden in the fourth commandment?
The sins forbidden in the fourth commandment are, all omissions of the duties required, (Ezek. 22:26) all careless, negligent, and unprofitable performing of them, and being weary of them; (Acts 20:7,9, Ezek. 33:30–32, Amos 8:5, Mal. 1:13) all profaning the day by idleness, and doing that which is in itself sinful; (Ezek. 23:38) and by all needless works, words, and thoughts, about our worldly employments and recreations. (Jer. 17:24,27, Isa. 58:13)