Commento su I Cronache 28:9

and worship Him with a whole heart Heb. בְּלֵב שָׁלֵם. It is not stated בְּלֵבָב שָׁלֵם, which would mean two hearts, but בְּלֵב שָׁלֵם, that you shall have but one heart for our Father Who is in heaven. And so did the liturgical poet set down (in the Kedushah of Musaph of the first day of Rosh Hashanah): “You have two hearts like one for the One.” Similar to this, [we find in] (I Kings 8:61): “Let your heart [therefore] be whole (שָׁלֵם) with the Lord our God.” It is not written שְׁלֵמִים but שָׁלֵם: your two hearts will be one whole heart. And so it is explained (Gen. 18:5): “... and refresh your heart (לִבְּכֶם), afterwards you may pass on.” This teaches us that the angels have only one heart, and also in the future it will be so, as it is written: (Ps. 48:14): “Give heed (לִבְּכֶם lit., your heart) to its walls.”

for the Lord seeks all hearts Here it is appropriate to say לְבָבוֹת ; the Lord seeks all hearts, whether good or bad.

and He understands the thoughts of every creation In Genesis Rabbah (9:3), we learned: “Before a creature is created, the Holy One, blessed be He, understands what the person is destined to think.”