Al-Kāfi - Volume 6 > The Time in which Slaughtering is not Desirable
Hadith #3

عَلِيُّ بْنُ إِسْمَاعِيلَ عَنْ مُحَمَّدِ بْنِ عَمْرٍو عَنْ جَمِيلِ بْنِ دَرَّاجٍ عَنْ أَبَانِ بْنِ تَغْلِبَ قَالَ سَمِعْتُ عَلِيَّ بْنَ الْحُسَيْنِ ( عليه السلام ) وَ هُوَ يَقُولُ لِغِلْمَانِهِ لَا تَذْبَحُوا حَتَّى يَطْلُعَ الْفَجْرُ فَإِنَّ اللَّهَ جَعَلَ اللَّيْلَ سَكَناً لِكُلِّ شَيْ‏ءٍ قَالَ قُلْتُ جُعِلْتُ فِدَاكَ فَإِنْ خِفْنَا فَقَالَ ( عليه السلام ) إِنْ خِفْتَ الْمَوْتَ فَاذْبَحْ .

3. Ali ibn Tsma’il has narrated from m ibn ‘Amr from Jamil ibn Darraj from Aban ibn Taghlib who has said the following: “I once heard Ali ibn al-Husayn, ‘Alayhim al-Salam, saying to his servants (slaves), ‘Do not slaughter any animal before it is dawn because Allah has made the night for everything to rest.’ I then asked him (the Imam) saying, ‘I pray to Allah to keep my soul in service for your cause, what happens if we are afraid?’ He (the Imam) then said, ‘If you are afraid of death then you can slaughter.’”