Is it permissible to build an iron fence around a grave, about a handspan high, to identify it and protect it from floods, knowing that the fence consists of vertical posts connected by four horizontal iron bars?

The authentic Sunnah forbids plastering graves, raising them, or building upon them, out of fear of temptation, polytheism, and squandering wealth. It is mentioned in a hadith that the Messenger ordered Ali not to leave any raised grave without leveling it. It is permissible to fence graves to the extent necessary to protect them from predators or floods. However, raising them merely for identification is not legislated; rather, it falls under the general prohibition.