I am hoping you can tell me the basis for “Ruqya” (hadith?) and can it be read over regular water/oil ?
There isn’t any specific hadeeth on one particular Ruqya. However, the best Ruqya would be to recite Suratul Fatiha, ayatul Kursi, the last two ayah of Suratul Baqarah and the last 3 Surah of the Quran. you read these 3,5 or 7 times and you blow in your hands and wipe the place that you complain of. You can do that and blow on oil or water, preferably zamzam water. You can drink that water or wash the affected area with it.