Torah · Halacha YomitHalachot of Pesek ResheRabbi Uri Nahum · October 13, 2026 · 39 Melachot-15Play+30Position0:00—Save⌄ShareLights, intentions & how it works.Transcript0:00So the last couple of days we've been talking about the halachot of0:05p'sik reisha. Of course, like we said, this is a rule throughout the whole halachot of Shabbat. It's not just in one example.0:10We've brought a few examples, but you always have to ask yourself: what is the act?0:17What is your kavanah? Because p'sik reisha depends on0:21kavanah. If your intention is for the issur, it doesn't make a difference if it's direct or0:25not direct; it's always going to be0:26asur. So let's give the classic case of p'sik reisha is a guy forgets the light in his fridge, and he's opening the door.0:34The act is opening the door. What happens when you open the door is automatically the lights go on.0:39Now, if your intention is the light should go on, if, for example, it's dark in your kitchen0:44and you're trying to find your baby bottle and the kid is crying, right,0:48and you were sent down with that mission today to get the milk and the things,0:52so now you can't find the baby bottle, so you say, Oh, I got a great idea.0:54You open up the fridge, and ta-da, vahi or, and there's light in the room.1:00So of course that's asur. That's like putting on the light.1:03That's not p'sik reisha; that is putting on the light.1:06We're talking about over here that that's not the case.1:08The case is it's dark in the room.1:10You open the fridge because you want to get something from the fridge.1:13In that case, that you open the door and the light goes on,1:16that's called a1:17p'sik reisha. Your intention was not for the light, but you know that when you open the fridge door, the light would go on.1:22So it's very important that p'sik reisha, we're talking about that your kavanah is never for the issur.1:26Your kavanah is to do something mutar, and an issur results from it.1:30In that case, in those scenarios, is what we said. Now either way, like we said, it's1:35asur, but there will be cases where p'sik reisha could be mutar.1:39Now for this, to be allowed to know when it's mutar and when not mutar,1:43you have to be knowledgeable very well in the halachot of Shabbat,1:47of what is asur mid'oraita and what is1:51asur mid'rabbanan. Because there's a rule, I'm going to say it right now, and if you're not familiar, it's going to sound very confusing.1:56Psik reisha d'lo nicha lei mutar.1:59Okay, what does that mean?2:00Psik reisha, like we just said, explained what psik reisha is.2:03If the issur that's resulting from what you're doing is only issur2:10d'rabbanan, and you couldn't care less for it, it doesn't make a difference for you whatsoever,2:15then in that case it would be mutar if there's no other choice.2:19Okay?2:21So that would be, for example, here's a very common example.2:27Sometimes you walk by and there's like these little cameras or whatever,2:31and they have this little light that flashes on and off,2:34okay?2:35That light that goes on and off, now what you're doing is you're just walking.2:39You're walking in your house, right, and this camera over there has this little light that goes on.2:44It's a motion sensor kind of when you walk by.2:46You're really supposed to shut it off before Shabbat,2:48right?2:49That motion sensor, that light that goes on, it's supposed to take care of that light before Shabbat.2:54If you didn't and walk by it,2:56I remember once somebody asked me a question. He said he was staying by somebody's house,3:00he didn't realize, and he's sitting there crawling on the floor,3:02which I don't think it helped anyone because the camera gets on anyway.3:05But it was like a little blue light that, you know,3:09kind of like what you see over here by this phone, that little blue light.3:12So it senses when somebody walks by.3:14Now the issur that's happening over there when you walk by,3:18you're doing the act of walking.3:20Walking is3:20mutar, but by walking you are causing for sure an issur to happen, which is3:26psik reisha. But this issur is only3:28a issur d'rabbanan. We hold that lights to go on, especially all the lights that we use today,3:33are only3:35a issur d'rabbanan. If you couldn't care less for it, which is obviously the case,3:38you don't care, that light does nothing for you.3:40It doesn't help you, it doesn't do anything for you.3:41So therefore it's a psik reisha d'rabbanan, right?3:45The issur that's happening3:47is d'rabbanan. Lo nicha lei means you couldn't care less for it.3:49It doesn't help you, it doesn't benefit you.3:52And in that case, since there's no other choice,3:54that means if you could have walked this way, don't walk this way.3:56Why are you walking that way?3:58Then it would be4:00mutar. Okay,4:01so let's now bring it to a more practical example.4:04You have that non-Jewish neighbor that likes to keep his lights on with a motion sensor,4:08and only on4:09Shabbat. The whole week, no,4:13it doesn't have it on.4:13Only on Shabbat because he wants you to put it on.4:17I don't know, right? You know those guys.4:18Okay,4:18so now, if it's a Jewish neighbor, if it's your lights and it has a motion sensor,4:22shut it off before Shabbat.4:23But if it's the goy and you have to walk by to get to your house,4:27if you could come the other way, of course you come the other way.4:30For example, on my block, I have a goy like that,4:32right?4:32The reason, it just feels like he only does it on Shabbat.4:35So I could go into the street and avoid it.4:38I should go in the street and avoid it.4:39But if I can't avoid it for whatever reason,4:43then the lights, again, being that they're LED,4:46I'm getting too complicated for4:49Sefardim, it's much more lenient, so a lot of poskim hold it's only4:52derabanan, so it's a psik reisha in4:55a issur derabanan. And if you don't care for the light,4:57if you care for the light because you want to see what's in front of you, fine.4:59But usually we have street lights, we have other sources of light,5:02so then it would also be mutar.