What is the ruling on speaking with a girl via Facebook, considering each other as siblings and only for the purpose of mutual benefit, especially since the mothers have approved of it?

Speaking with a non-mahram woman without necessity is a gateway to temptation (fitna). Imam Al-Khadimi stated that it is impermissible to speak with a young non-mahram woman without necessity, as it is a cause for temptation. It is advised to refrain from conversing with girls via social media and to beware of Satan's enticement under the guise of "brotherhood" or "advice," for this is his deception. One must occupy their time with what benefits them in their religion and their worldly life.