פירוש על קהלת 12:3

Trembling. Trembling.

“on the day that the guards of the house will tremble, the men of valor will be bent, the grinders will cease because they have dwindled, and it will be dark for those who gaze through the windows” (Ecclesiastes 12:3);
“On the day that the guards of the house will tremble” – these are the ribs; “the men of valor will be bent” – these are one’s arms. Rabbi Ḥiyya ben Rabbi Neḥemya says: These are one’s ribs. “The grinders will cease” – this is the stomach; “because they have dwindled” – these are the teeth; “and it will be dark for those who gaze through the windows” – Rabbi Ḥiyya ben Rabbi Neḥemya says: These are the edges of the lungs, from which the sound of the voice emerges.

The preservers of the house. These refer to the ribs and flanks, that protect the entire body’s cavity.⁶Alternatively, these refer to the hands and arms. (Metsudas Dovid)