In plain words
So forgiving him and letting him go is the very best way. Not only that. As much as I weep for the loss of my sons, so much will his mother grieve too if you kill Aśvatthāmā, will she not! Merely by killing him my children will not come back, will they! To bundle up such a sin for the sake of those who are gone is very wrong. Those who have love for God do not commit such a misdeed. So you must not kill him,” she pleaded. At that time Draupadī showed great forgiveness and Śānti. We must cultivate such Śānti. We must put violence far away. We must conquer hatred by Śānti. Hearing the words Draupadī spoke with such patience and Śānti, Bhīma grew furious.
She feels no anger that he seized and killed her sons; this child-killer she tells us to let go; Draupadī is out of her mind! Is this fellow a brahmin? Why let him go? Kill him, here and now! If you do not kill him, with my fist's blow I will split his head apart: watch, all of you!
Saying, ‘This mad Draupadī is falling at the feet of Aśvatthāmā, who killed her sons!’, Bhīma, in anger he could not contain, clenched his fist, his eyes gone red, and went at Aśvatthāmā. “Draupadī! Has some madness seized you? Why are you trying to save this villain who mercilessly cut your sons' throats? With a blow of my fist I will smash his head to pieces. Do not get in my way,” he said. But Draupadī fell at Bhīma's feet and pleaded with him to be calm. Those around were watching in great astonishment; they thought, ‘Are there mad women like Draupadī anywhere in the world?!’ But if such madness seized everyone, this world would be set right.
“Draupadī! I made a vow that I would kill Aśvatthāmā, did I not! If I cannot keep that word now, is it not a disgrace to me?” said Arjuna.