Celebrating birth and wedding anniversaries

Assalamu Alaikum
What is the ruling on celebrating birthdays? Celebrating children's birthdays or giving them gifts; making some arrangements for cooking and eating if there are only family members and no outside guests; or gathering children on children's birthdays; throwing them parties; exchanging gifts between children; feeding and entertaining them; ... sending children to such gatherings; what is the Sharia ruling on these? And exchanging gifts on wedding anniversaries or spouses' birthdays, or getting ready, or going out on the same day, arranging food and drink, is all this permissible or not? And if the arrangements are not made on the same day, but are made two or four days before or after the particular date, and obviously, the arrangements are being made in this respect, then, what is the ruling on this? And if this is unlawful, is there any permissible way of doing it? Please give a detailed answer. Jazak Allah Khaira.

الجوابُ حامِدا ًو مُصلیِّا ً

Celebrating children's birthdays or wedding anniversaries is not proven from the life of beloved Nabi Sallallahu alaihi Wa Sallam (peace and blessings of Allah be upon him), the Companions Radhiyallahu Anhum (may Allah be pleased with them all), and the righteous predecessors Rahimahumullah (may Allah have mercy on them). Rather, it is an invention of non-Muslims. Therefore, Muslims must avoid following them in celebrating children's or wedding anniversaries and performing other customary activities on this occasion. However, if family members, loved ones, and relatives gather on a day without following the birthday customs and invited for meals etc or lawful outings and entertainment are arranged, then it is permissible according to Islamic law.

مأخَذُ الفَتوی

کما فی مرقاة المفاتیح: عن ابن عمر۔رضی اللہ عنه۔ قال: قال رسول اللہ ﷺ من تشبه بقوم فھو منھم۔رواہ احمد وابوداؤد
وفی مرقاة المفاتیح: ای من تشبه نفسه بالکفار مثلاً: فی اللباس وغیرہ او بالفساق والفجار اھ(8/155)۔