Majmu' al-Fatawa - Ibn Taimiya - (25/329)

He was asked:

About Muslims who prepare food like that of the Christians at Nayrūz and observe the other festivals, such as Epiphany, Christmas, Lentil Thursday, and the Saturday of Light, and about those who sell Christians things they use for their festivals: is it permissible for Muslims to do any of this or not?

He replied:

Praise be to Allah. It is not lawful for Muslims to imitate them in anything distinctive to their festivals, whether food, clothing, bathing, lighting fires, or suspending customary activities relating to livelihood, worship, or anything else. Nor is it lawful to hold a feast, give gifts, or sell things that assist in these observances for that purpose. Nor may children and the like be allowed to engage in the games associated with these festivals, nor may adornments be displayed.

In short, Muslims must not mark their festivals with any of their distinctive observances. Rather, their festival days should be like any other days for Muslims, who must not single them out for any practices distinctive to them.

وَسُئِلَ: عَمَّنْ يَفْعَلُ مِنْ الْمُسْلِمِينَ: مِثْلَ طَعَامِ النَّصَارَى فِي النَّيْرُوزِ. وَيَفْعَلُ سَائِرَ الْمَوَاسِمِ مِثْلَ الْغِطَاسِ وَالْمِيلَادِ وَخَمِيسِ الْعَدَسِ وَسَبْتِ النُّورِ وَمَنْ يَبِيعُهُمْ شَيْئًا يَسْتَعِينُونَ بِهِ عَلَى أَعْيَادِهِمْ أَيَجُوزُ لِلْمُسْلِمِينَ أَنْ يَفْعَلُوا شَيْئًا مِنْ ذَلِكَ؟ أَمْ لَا؟ فَأَجَابَ: الْحَمْدُ لِلَّهِ، لَا يَحِلُّ لِلْمُسْلِمِينَ أَنْ يَتَشَبَّهُوا بِهِمْ فِي شَيْءٍ مِمَّا يَخْتَصُّ بِأَعْيَادِهِمْ لَا مِنْ طَعَامٍ وَلَا لِبَاسٍ وَلَا اغْتِسَالٍ وَلَا إيقَادِ نِيرَانٍ وَلَا تَبْطِيلِ عَادَةٍ مِنْ مَعِيشَةٍ أَوْ عِبَادَةٍ أَوْ غَيْرِ ذَلِكَ. وَلَا يَحِلُّ فِعْلُ وَلِيمَةٍ وَلَا الْإِهْدَاءُ وَلَا الْبَيْعُ بِمَا يُسْتَعَانُ بِهِ عَلَى ذَلِكَ لِأَجْلِ ذَلِكَ. وَلَا تَمْكِينُ الصِّبْيَانِ وَنَحْوِهِمْ مِنْ اللَّعِبِ الَّذِي فِي الْأَعْيَادِ وَلَا إظْهَارُ زِينَةٍ. وَبِالْجُمْلَةِ لَيْسَ لَهُمْ أَنْ يَخُصُّوا أَعْيَادَهُمْ بِشَيْءٍ مِنْ شَعَائِرِهِمْ بَلْ يَكُونُ يَوْمُ عِيدِهِمْ عِنْدَ الْمُسْلِمِينَ كَسَائِرِ الْأَيَّامِ لَا يَخُصُّهُ الْمُسْلِمُونَ بِشَيْءٍ مِنْ خَصَائِصِهِمْ.