What is the ruling of the Sharia on a brother speaking with girls via Messenger for long hours, and what is the ruling on the words of a girl who claims she does that to guide him, even though the brother exceeds respectful speech with her?

A brother's advice to his brother to stop talking to foreign women and forming relationships with them is a good deed, for advice is the foundation of religion, and enjoining good and forbidding evil are characteristics of this Ummah. Islam has forbidden relationships between foreign men and women except within the framework of lawful marriage. Furthermore, talking to foreign women without need and enjoying their speech is not permissible. The proof for this is the Prophet's (peace and blessings be upon him) saying: "The two eyes commit zina by looking, and the two ears commit zina by listening, and the tongue commits zina by speaking, and the hand commits zina by touching… and the foot commits zina by walking… (the rest of the hadith)."