Muhammad bin Ishaq (may Allah have mercy on him) relates: When the bier of Sayyiduna Sa'd (may Allah be pleased with him) was carried, his mother was weeping and saying: "Alas for the mother of Sa'd! How sensible and diligent he was, and a chief who filled the gap (of his people)!" At that the Messenger of Allah (peace and blessings be upon him) said: "Every woman who weeps (over the dead) lies, except the one who weeps over Sa'd bin Mu'adh."
Hadith Referenceالمعجم الكبير للطبراني / باب السين / 5310