Shaykh Maulana Usman Muneeb
Benefits and Issues:
➊ Both of the aforementioned narrations are weak. In contrast, responding to greetings (salam) with a gesture of the fingers or palm has been described as the practice of the Jews and Christians, and resemblance to them has been prohibited. (Jami‘ al-Tirmidhi and al-Silsilah al-Ahadith al-Sahihah, no. 2194)
Imam Nawawi rahimahullah has written that if a person is unable to give salam verbally, then he may give salam with a hand gesture along with the tongue; for example, if someone is far away, or is mute, or is in prayer, then he may respond to salam with a hand gesture. (Fath al-Bari)
Shaykh al-Albani rahimahullah states in Jilbab al-Mar’ah al-Muslimah that the narration Imam Nawawi rahimahullah used as evidence is weak due to Shahr ibn Hawshab, and therefore, one should not give salam by hand gesture in any way, because this resembles the Jews and Christians. (Jilbab al-Mar’ah al-Muslimah, p. 195)
According to our inclination, one should avoid giving salam by hand gesture as much as possible. However, in unavoidable situations, as Imam Nawawi rahimahullah has stated, it is permissible to respond to salam with both a hand gesture and the tongue. And there are two reasons for this:
(a) Although the narration in Jami‘ al-Tirmidhi and others regarding giving salam by hand gesture is weak due to Shahr ibn Hawshab, mention of this is also found in the reports from the Companions, even though there is criticism in all the chains. Furthermore, it is only the act of giving salam by gesture alone that is mentioned as resembling the Jews and Christians. By pronouncing it with the tongue, the resemblance is to some extent removed.
(b) Responding to salam by gesture during prayer is established from authentic hadiths, from which it is understood that there is allowance for this in exceptional cases.
➋ In the present era, the custom of greeting with a hand gesture or saying “hello,” even when the other person is nearby, is certainly an imitation of the Jews and Christians, which must be avoided.
Source: Fadlullah al-Ahad: Urdu Commentary on al-Adab al-Mufrad, Page: 1003