Is it permissible to greet a disbeliever with something other than ‘Salam’?
The Messenger of Allah said:
“Tomorrow, I am going to meet the Jews. So, do not initiate the greeting of ‘Salam’ to them. If they greet you with ‘Salam,’ then say: ‘Wa ‘alaykum.’“
[‘Sahih al-Adab al-Mufrad’; # 838]
In ‘Silsilat al-Ahadith as-Sahihah’ (2/320), al-Albani commented:
“So, if it is asked: ‘Is it permissible to initiate a greeting to a disbeliever with something other than ‘Salam,’ such as by saying ‘How are you,’ ‘Good morning,’ etc.?’
I say – and Allah Knows best – that it is allowed, since the prohibition mentioned in the hadith is specifically in regards to the ‘Salam,’ and what is intended by it is the Islamic greeting that contains one of Allah’s Names, as in the saying of the Prophet: “‘as-Salam’ is one of Allah’s Names that He has descended upon the Earth. So, spread ‘as-Salam’ between yourselves.” (‘Sahih al-Adab al-Mufrad’; # 760)
And from what supports what I have said is the narration of ‘Alqamah: “Verily, ‘Abdullah bin Mas’ud greeted the disbelieving peasants with a hand gesture.” (‘Sahih al-Adab al-Mufrad’; # 840)
So, Ibn Mas’ud permitted the initiation of greetings to the disbelievers by way of hand gesture, since this manner of greeting is different from the greeting of ‘Salam’ that is specific for the Muslims.”
And Allah Knows best.