Musnad Ahmad 1153:1982

Yazid narrated to us, he said: Ibn Abi Dhi'b informed us, from al-Harith ibn 'Abd al-Rahman, from Abu Salamah, from 'Aishah, she said: The Messenger of Allah, peace and blessings of Allah be upon him, took my hand, then pointed to the moon and said: "O 'Aishah, seek refuge in Allah from the evil of this, for this is the *ghasiq* (darkness) when it settles."