The verse states, ‘My son Efraim is dear to me, my frolicking child, the more I speak of him the more I remember him, so my loins long for him, and the more I have mercy on him’. This verse refers to someone learning Torah, and Hashem is like his teacher, helping him understand what he learns, as we say in the blessing on the Torah, ‘Who teaches Torah to His nation’. Furthermore, the words he utters as he learns are repeated simultaneously by Hashem. This is what the verse means, ‘My son Efraim is dear to me’, for a son is dear to his Father, ‘when he frolics’ with His Torah. The reason that Hashem likes it so much is because, ‘the more I speak of him’, the more Hashem repeats what he learns, ‘so [Hashem] longs for him, and the more [Hashem] has mercy on him’, for through his learning Hashem remembers him eternally and supplies him with his needs.
כ״ח באלול ה׳תשפ״א
"והאמת בלתי שום ספק כלל, שאם היה העולם כולו מקצה עד קצהו פנוי חס ושלום אף רגע אחד ממש מהעסק והתבוננות שלנו בתורה, כרגע היו נחרבים כל העולמות, עליונים ותחתונים, והיו לאפס ותוהו חס ושלום". (נפש החיים) 1