Answer:

Swearing

"Lord, I'm sorry for all of what I say, I apologize and please forgive me, I promise that I will change and I will avoid saying bad words again. Lord, I know you'll help me and I know I will change."

Explanation:

Swearing is common, and it's a sin because your saying words that is bad and shouldn't be said.

I tried T_T

I hope it helps tho, i did my best :V

Remember to always pray <3