Theophylact of Ohrid

But He blesses those who keep the word of God, not, however, in order to deprive His Mother of blessedness, but in order to show that even She would have received no benefit from having given birth to Him and nursed Him at Her breast, if She had not possessed all the other virtues. He says this also because it is timely. Since those who envied Him and did not listen to His words reviled those who did listen, He, contrary to them, especially blesses those who listen. …

Commentary on Luke ↗

Bede

But he said: Rather, blessed are those who hear the word of God and keep it. The Savior beautifully agreed to the testimony of the woman, meaning not only her who was worthy to physically bear the Word of God, but also all those who spiritually, by the hearing of faith, conceive the same Word, and in the custody of good works strive either to bear it in their own heart or in the hearts of others, and as if to nurture it, asserting that they are blessed. …

On the Gospel of Luke ↗

Bonaventure

"A certain woman from the crowd, raising her voice, said to him: Blessed is the womb that bore you, and the breasts that nursed you." And Jesus said: "Rather, blessed are those who hear the word of God and keep it." Not only is she blessed who conceived and nursed him, but also those who follow her. And who are they? Those who hear the word of God and fulfill it. …

Collationes de Septem Donis, Collation 6 ↗