הלכה על ברכות 61:27

We learn many essential halakhot from the prayer of Ḥana, who stood and begged God to remember her and grant her a son. Her prayer was accepted and she merited giving birth to Shmuel the prophet, who was the greatest prophet of Israel behind Moshe. The verse states: “Ḥana spoke to her heart, only her lips moved, and her voice was not heard” (1 Shmuel 1:13). The Sages teach: “‘Spoke to her heart’ – from here [we learn] that the person praying must focus his heart. ‘Only her lips moved’ – from here [we learn] that the person praying must articulate the words. ‘Her voice was not heard’ – from here [we learn] that it is prohibited to raise one’s voice while praying” (Berakhot 31a).