Upon hearing his wife's account of a divine visitor and the promise of a son, Manoah feels a strong desire to take an active role in God's plan. He turns to God in deep, intense prayer [מצודת ציון], pleading that the heavenly messenger be sent back specifically for his sake [אברבנאל, ביאור שטיינזלץ]. His request is simple but urgent: he asks that the man of God return to teach and guide them on exactly how to raise the child that is to be born [רש״י, רד״ק, מצודת דוד].
Manoah's plea for a second revelation stems from a missing piece of information. When his wife first told him about the encounter, she shared the dietary restrictions placed upon her but kept quiet about the command to never cut the child's hair. Because of this omission, Manoah assumes the visitor only gave instructions for the mother and provided no guidance regarding the child himself [אלשיך, מלבי״ם]. Believing that the responsibility of raising the boy belongs to both parents equally, he reasons that the messenger should come to both of them to deliver the necessary instructions [אלשיך, צאינה וראינה].
Furthermore, Manoah understands that a child designated as a Nazirite from the womb is a unique divine event, entirely different from the standard laws of someone who voluntarily takes a vow later in life. He worries that this rare status might require additional actions or special ways of raising the child beyond the familiar rules. To ensure they do not make a mistake, he asks God for the messenger to clarify exactly what is expected [מצודת דוד, מלבי״ם, אברבנאל].
This entire episode highlights a clear spiritual gap between Manoah and his wife. He remains unaware that the messenger had already given her the full instructions regarding the boy, simply because she was more spiritually prepared and worthy of receiving the prophecy than he was. Additionally, the return visit is designed to happen through the wife for a highly practical reason: only she can positively identify the visitor and confirm that he is the exact same man of God who appeared the first time [אלשיך, אברבנאל].