Musnad Abu Ya'la al-Mawsili 150:26

Ishaq narrated to us, Abd al-Samad ibn Abd al-Warith narrated to us, Muhammad ibn Mahzam al-Shi'ab narrated to us, Abd al-Rahman ibn al-Qasim narrated to us, from al-Qasim, from Aisha, that the Prophet (peace and blessings of Allah be upon him) said: "As for whoever is given his portion of gentleness, he has been given his portion of the good of the world and the Hereafter. And whoever is deprived of his portion of gentleness, he has been deprived of his portion of the good of the world and the Hereafter."