Question: Congratulating a person on the day of their birthday via text message only and not having a party [for that occasion]. [Is that allowed?]
Answer: “A birthday is a day a person should comfort/console himself because a year of his life has passed. Following that, he should be given condolences [on such a day] not congratulations. The arrival of such a day should [result in to him being] given condolences. The legislated congratulations should be given in an issue that benefits a person in the worldly life or hereafter. If he is granted a child, money comes to him, if he earns [a profit] in business, he performs a righteous action etc. A person is congratulated for that. As for his days passing away and he did not use this time in the obedience of the Lord of Might and Honor, then he is not congratulated on account of it. So like that, you find the festivals in Islam are connected to acts of worship. Eid ul-Fitr is after fasting Ramadan and giving Zakatul-Fitr [and congratulations are given] to the people for these actions, which they performed in this virtuous month, from fasting, standing in prayer, and recitation. Likewise, Eidul-Adha. It is after the season of worship, the ten days of Dhul-Hijjah, a season that is virtuous wherein the deeds are multiplied, and it is specified with something of righteous deeds. Or that which is connected to the Day of Nahr wherein there is slaughter and it has a high status and lofty station. Or that which is connected to the rites of Hajj to the Sacred House and a person participating himself or hoping to participate in it while he is not able to. He is rewarded. Likewise what is connected to the day of ‘Arafah and the congratulations here is due to a time period wherein there are acts of worship at that time. As for making the passing of time [i.e. birthdays] the reason for congratulating [others], then this is not from the Legislated affairs”.
Faisal bin Abdul Qaadir bin Hassan