Yes, you can reuse the water from soaked pulses for cooking, as it contains nutrients leached from the pulses during soaking. This can add flavor and nutritional value to your dish.
When pulses like beans, lentils, or chickpeas are soaked, some of their nutrients, including vitamins and minerals, dissolve into the water. Reusing this water means you're retaining those nutrients instead of discarding them. Furthermore, the soaking water often carries some of the flavor of the pulses, which can enhance the taste of your cooked dish. Simply use the soaking water as part of the liquid required in your recipe. For example, if you're making a lentil soup, use the water the lentils were soaked in as part of the broth. Be sure to rinse the pulses well before soaking to remove any dirt or debris. If the soaking water appears cloudy or has an off-putting smell, it's best to discard it.
If you're concerned about potential digestive issues, such as gas, from consuming pulses, consider discarding the soaking water. Soaking helps to remove some of the indigestible sugars that cause flatulence. Discarding the water removes these sugars more effectively than reusing it.