Wa alaykum salam wa rahmatuLlahi wa barakatuHu,
In regards to using tobacco products, this is a point on which the scholars differ(ed). Sayyid 'Alawi al-Saqqaf authored an article on this topic in which he highlighted and discussed the differences of opinion under the title Risalah fi Qam' al-Shahwah 'an Tanawul al-Tunbak wa al-Kaftah wa al-Qat wa al-Qahwah. Mustafa al-Babi al-Halabi Cairo, Egypt published this article in a collection of his articles under the title Majmu'ah Sab'ah Kutub Mufidah. This publication was funded by Salim b. Sa'd and his brother Ahmad from Surabaya in Eastern Java, Indonesia.
Firstly, in the article, 'Alawi al-Saqqaf points out that this is a matter on which the Lawgiver has not explicitly stated a ruling. There is not any text stating whether this particular action is lawful or unlawful. Using tobacco, as the author mentions, is from the matters that are 'mushtabihat' as mentioned in the famous hadith related by Imams Bukhari and Muslim on the authority of Nu'man b. Bashir that the Prophet Muhammad (upon him be peace) said, 'The lawful is clear and the unlawful is clear. Between them are mushtabihat, they [their rulings] are not [easily] known amongst the masses.'
Then, he related three opinions on the issue. They are:
(1) It is unlawful. Saqqaf related this from Muhammad Hayat al-Sindi, Abu Bakr b. Qasim al-Ahdal, Imam 'Abd Allah al-Haddad, and the majority of Sufis. Others from amongst the Shafiyyah have also held this opinion, such as Najm al-Din al-Ghazzi, Qalyubi, and Ibn 'Allan.
(2) It is not unlawful. This Saqqaf related from Muhammad b. Isma'il al-San'ani, 'Abd al-Ghani al-Nabalusi, al-Zayyadi, and others. From amongst the Shafiyyah, the opinion that it is permissible is also related from Hifni, Halabi, Rashidi, Shabramallisi, and 'Abd al-Qadir b. Muhammad b. Yahya al-Husayni al-Tabari al-Makki who authored a treatise on the topic under the title 'Raf' al-Ishtibak 'an Tanawul al-Tunbak.' This is also Shawkani's opinion.
(3) The third opinion related is that a ruling of lawfulness or unlawfulness cannot be generalized. Here, the scholars discussed the ruling by way of it being detailed (ar: tafsil). The details mentioned under this third opinion discuss other aspects relevant to tobacco use that may be governed by a hukm shari'.
For example, spending money in a wasteful way is not permissible, so if it would lead to this, then it would not be acceptable from that angle; or to do something that causes damage and harm to one's body, like consuming poison. So for one to become a heavy, long-term consumer of a known carcinogen could be considered problematic. Another detail mentioned, which is also related by Sharwani from some of the Shafiyyah in his hashiyah on Tuhfat al-Muhtaj 3/69, is a ban on tobacco by the ruler. He says that if tobacco is consumed in areas affected by the ban, then anyone who violates that is transgressing. While anyone who uses tobacco in another place, like at home, is not. This is another way it could be unlawful because of rulings intrinsic to other acts associated with tobacco use.
(4) There is a fourth opinion that 'Alawi al-Saqqaf did not relate. Some say it is disliked (ar: makruh). This is related from 'Abd al-Hamid al-Sharwani min as-habina and some related it from the Hanafi Ibn 'Abidin.
Various groups of scholars exerted themselves by studying the issue in order to try and determine the ruling. A lot of the difference between the scholars stems from them identifying certain issues associated with tobacco use that must be avoided. And then others counter-arguing against those points, calling into question the veracity of establishing the mentioned associations in this case. Applying the issue of squandering wealth, a bad smell, or the possibility of harm are all argued both for and against.
The Qur'an, the Sunnah, and scholarly consensus do not provide a ruling here. When the primary source evidence does not state a ruling, the continuation of the asl is then the basis for a fatwa. And in the usul, many incline to that the default ruling (ar: asl) for substances is that they are permissible unless evidence establishes otherwise. In the arguments of those stating it to be permissible, they argue this point. That: al-asl fi al-ashya' al-ibahah. In fact, Zarkashi stated that Imam Rafi'i related this from the As-hab.
What is known in regards to tobacco use, especially heavy, long-term use, is that it causes cancer, which is definitely harmful. Furthermore, a heavily addicted smoker spends thousands on the habit annually, in some cases even to the detriment of others he is obligated to financially support. This might not be the case with everyone, but it is surely the case with some. And in Jam' al-Jawami' 2/325, Ibn al-Subki mentioned that,
أصل المضار التحريم وأصل المنافع الحل
'The default ruling of what causes harm is that it is unlawful, and the default ruling of what produces benefit is that it is lawful.'
This tafsil is preferred by Ibn al-Subki, Jalal al-Din al-Mahalli, and others. The consideration of harm to the extent that a ruling of unlawfulness would be established does seem to be differed on in the arguments presented on the topic. As with other matters of fiqh and fatawa, differences of opinion are respected. If one does not take the view that it is unlawful, it would still be best to avoid it khurujan min al-khilaf.
And Allah knows best.
Answered by Shaykh Yaqub Abdurrahman