Sforno on Genesis 16:13/ספורנו על בראשית ט״ז:י״ג

1ותקרא שם ה, the meaning of the words ותקרא שם ה', is prayer. It refers to the kind of prayer in which one praises the Lord, or thanks Him. This prayer may be offered silently, in one's mind or with words. The source for this definition is found in Berachot 32: "as a rule a person should first address G'd by praising Him, before beginning to pray." [to tell G'd of his requests from Hi. Ed.] This thought is reflected in the inscription in most synagogues on the Holy Ark שויתי ה' לנגדי תמיד, "I am ever mindful of the Lord's presence" (Psalms 16,8) The word קרא for prayer is also found in Lamentations 3,55 קראתי שמך ה', "I have prayed to You o Lord," as well as in Psalms 79,6 ושמואל בקוראי שמו, "as well as the prophet Samuel who would pray (successfully) to Him." Also the well-known line כי שם ה' אקרא, (Deut. 32,3) is best translated as "for I will pray to the Lord," rather than as "I will proclaim the name of the Lord." Hagar's new insight, expressed by her saying אתה א-ל ראי, meant that whereas up until now she had assumed that revelations from G'd are confined to the house of Avram, she had now learned that G'd may reveal Himself in any location. This is in line with Baba Metzia 59 כל השערים ננעלו חוץ משערי דמעות, that although the gates of prayer have largely remained shut since the destruction of the Temple, the prayer of people complaining (shedding tears) of being dealt with unfairly by their fellow human beings have not been closed.