Do you need a comma in a compound predicate?
A compound predicate says two or more things about the subject. A common mistake people make is to insert a comma between two elements of a compound predicate. This comma adds a pause that creates distance between the subject and the predicate, so you should not include a comma in this case, just as you would not use a comma to separate a verb from its subject or object.
Here is an example that demonstrates the correct and incorrect ways to write a sentence with a compound predicate:
Correct: 'He scratched the cat’s head and rubbed his belly.'
Incorrect: 'He scratched the cat’s head, and rubbed his belly.'