Hariri cited fear of assassination and meddling by Iran and Hezbollah in the Arab world in his resignation speech.
Lebanese President Michel Aoun has refused to accept the resignation until he returns to present it in person.
Hariri drove straight from Beirut airport to read a prayer at the grave of his father, Rafik Hariri, whose 2005 assassination forced him into politics.
Asked if had a message for the Lebanese, who have largely united in demanding his return, Hariri said: “Thank you.”
Hariri is expected to take part in Lebanese independence day celebrations on Wednesday.