Praise be to Allah the Lord of the Worlds. May His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
Fireworks shouldn`t be bought or sold for the following reasons:
1- Disturbing the sick, the learners, and the sleeping, be they young or old.
2- Spending money for nothing. According to Sharia, it is prohibited to squander or be prodigal. Allah the Almighty Says {What means}: "Lo! the squanderers were ever brothers of the devils, and the devil was ever an ingrate to his Lord." {Al-Isra`, 27}. Allah also Says {What means}: "Eat ye of the fruit thereof when it fruiteth, and pay the due thereof upon the harvest day, and be not prodigal. Lo! Allah loveth not the prodigals." {Al-An`am, 141}.
Squandering refers to spending wastefully or extravagantly while being prodigal refers to spending a lot of money carelessly without thinking what will happen when there is none left.
3- The smoke from the fireworks could be harmful to health.
4- Fireworks could cause injuries and start fires, if not used properly. And Allah The Almighty Knows Best.