I want to ask about the bad karma of speech when cursing and insulting Buddha and enlightened beings.?

I have a question. When I was a child, about 6 years old, I accidentally said insulting and blasphemous words to the Buddha's name. To be more specific, I said the Buddha's name with vulgar and insulting words. It was a mischievous act of an ignorant child. But later when I grew up and realized my wrongdoing, I deeply regretted it. At that time, I did not think it was a serious insult. Now I am a Buddhist, but I am always worried that it will cause me the retribution of falling into hell? What should I do? I really need advice, thank you and I wish you peace. P/s: I know Buddha and enlightened beings are very compassionate and will not pay attention to the words of sentient beings. But I still worry about the bad karma of my speech. Maybe this is a silly question but it has haunted me for a long time.