Is there any basis in the books of Sirah for the saying: "The most sorrowful moments in history were when our mother Aisha opened the curtain and said to the Companions: 'The Messenger of Allah, peace and blessings be upon him, has died'"?

The news of the Prophet's death (peace be upon him) was a tremendous shock to the Companions. Some were bewildered or denied his death, like 'Umar (may Allah be pleased with him). When Abu Bakr (may Allah be pleased with him) arrived, he entered upon the Prophet (peace be upon him) and kissed him. Then he went out to the people and informed them of his death, citing the words of Allah the Almighty: "And Muhammad is not but a messenger. [Other] messengers have passed on before him. So if he was to die or be killed, would you turn back on your heels? And he who turns back on his heels will not harm Allah at all; but Allah will reward the grateful." At that, the people became certain of his death and wept.