The Messenger of Allah ﷺ delayed the night prayer until those who wished to pray had already prayed, those who were awake had remained awake, the sleepers had fallen asleep, and those who keep night vigil had begun their devotions. Then he came out and said, "Were it not that I would impose hardship on my community, I would have ordered them to pray at this time," or "this prayer," or something to that effect.
حدثنا أسود أخبرنا إسرائيل عن فضيل عن مجاهد
أمسى رسول الله ﷺ بصلاة العشاء حتى صلى المصلي واستيقظ المستيقظ ونام النائمون وتهجد المتهجدون ثم خرج فقال لولا أن أشق على أمتي أمرتهم أن يصلوا هذا الوقت أو هذه الصلاة أو نحو ذا
Its chain of transmission is daif. Abu Israil is al-Mulai, Ismail bin Khalifa, and he is daif, as we explained at 974. Fudayl is Ibn Amr al-Faqimi. The hadith will come again through the route of Abu Israil from Fudayl at 5292. The substance of the hadith is sahih, reported by Muslim in similar wording through the route of Hakam and through the route of Ibn Jurayj, both from Nafi from Ibn Umar 1:176-177, and likewise reported by Abu Dawud 1:161 and Nasai 1:93, both through the route of Hakam from Nafi. It will come in the Musnad through the route of Ibn Jurayj from Nafi at 5611, and through the route of Fulayh from Nafi at 6097.