Without more specific information, it is difficult to determine which Islamic holiday is being celebrated tomorrow. However, based on the search results, there are several upcoming Islamic holidays in the near future, including:

• Milad un Nabi: September 28, 2023
• Lailat al Miraj: February 7, 2024
• Lailat al Baraah: February 28, 2025

It is worth noting that the dates of Islamic holidays vary depending on the sighting of the moon and may differ between countries.