Answer
Wa `alaykum as-Salamu wa Rahmatullahi wa Barakatuh.
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
1- Congratulating Muslims and imploring Allah to bless them and guide them to that which is good while seizing the opportunity of the new Hijri year is an issue that falls within the domain of permissible acts regarding which there is no stated prohibition.
2- Thus, there is nothing wrong if Muslims congratulate one another, exchange cards and demonstrate their joy with the inception of the new Hijri year.
Responding to the question, the prominent Saudi scholar Sheikh `Abdul-Kareem Al-Khudayr, states:
Praying for Muslims and congratulating them using phrases that are not meant as a kind of a ritual act is religiously acceptable, especially when such congratulations or supplications are done on special occasions such as the Eids.
Indeed, seizing such happy occasions (such as the Eids or the new Hijri year) and exchanging congratulations in them is capable of cementing the ties of friendship and solidarity among Muslims.
Allah Almighty knows best.
Editor’s note: This fatwa is from Ask the Scholar’s archive and was originally published at an earlier date.
Source: Excerpted with modifications from www.islamqa.info