Siman 472

(29.) He greatly warned us not to accustom ourselves to smoking a pipe and to sniffing tobacco. And he extended this conversation and said it is fitting for a proper man not to accustom himself to this — for it is simply waste of Torah and prayer. And it is something that is not needed at all. And regarding cleanliness — the pipe smoke is of no help at all. Particularly one who is already habituated to pipe smoking — it certainly helps him not at all, for something habitual helps not at all as is known to experience. And it is already explained [Sichos HaRan 30] that one need not confuse oneself with the matter of... one need not concern oneself with cleanliness only at the time when one truly needs the privy, and beyond that one need not look at this at all. And he said of himself: although he himself is accustomed to raise the pipe smoke, nevertheless before prayer he does not take the pipe in his hand at all. In all his days he never raised the pipe smoke before prayer. And to smell tobacco he said: this harms and wastes more than the service of the Creator. For one who is habituated to it cannot be without it even a single hour — and it is a great confusion and waste in the midst of Torah and prayer, especially at times when he has no tobacco, as is known to one habituated to it. And also it is hard to cast off the matter of tobacco for one who has become habituated to it. Therefore it is very good and fitting not to accustom oneself to these practices of the pipe (titun) and tobacco, which are not needed at all — only that they harm and withhold a person from Torah and prayer and the like: