Is the substance that comes out of wounds impure and does it nullify Wudu, and how can I pray if it is continuously flowing?

The aforementioned substance is impure but is excused due to hardship, and prayer with it is valid. However, it is recommended to wash it if it becomes excessive.

Al-Kharashi, in his commentary on Mukhtasar Khalil al-Maliki, stated: "The traces of boils, scabies, and the like, such as blood, pus, serous fluid, and water flowing from a fire blister that affects clothes or the body, are excused because it is difficult to guard against them if they flow on their own. However, if it (the blister) is peeled while it is flowing, then its trace is not excused if it is abundant, but a small amount is excused."

The substance exiting the body does not invalidate ablution, according to the more preponderant opinion.