The hadith appears in Jami' at-Tirmdihi in the book of virtuous of al-Hassan and al-Husain باب مناقب الحسن والحسين رضي الله عنهما :
"My mother asked me: 'When is your planned time - meaning with the Prophet (ﷺ)?' So I said: 'I have not had a planned time to see him since such and such time.' She rebuked me, so I said to her: 'Let me go to the Prophet (ﷺ) so that I may perform Maghrib (prayer) with him, and ask him to seek forgiveness for you and I.' So I came to the Prophet (ﷺ), and I prayed Maghrib with him, then he prayed until he prayed Al-'Isha. Then he turned, and I followed him, and he heard my voice, and said: 'Who is this? Hudhaifah?' I said: 'Yes.' He said: "What is your need, may Allah forgive you and your mother?' He said: 'Indeed, this is an angel that never descended to the earth ever before tonight. He sought permission from his Lord to greet me with peace and to give me the glad tidings that Fatimah is the chief of the women of Paradise, and that Al-Hasan and Al-Husain are the chiefs of the youths of the people of Paradise.'"
and was graded as hassan. And sheikh al-Albani compilled it in his Sahih at-Tirmidhi.
Parts of the hadith can be found in many other hadith collections, and many of these don't necesarrily seem to confirm that Hudaifah and the prophet were continousely in a mosque and none of the I consulted commentaries addresses this point. As for the part you refer to it only appears in Musnad Ahmad (Which is close in wording to that of at-Tirmidhi).