I recently asked a question regarding hatarat nedarim for Tehillim I have taken upon myself, and your answer sparked another question –
A few months ago, I decided to try and recite 10 perakim of Tehillim each Shabbat afternoon – While I didn’t explicitly say to myself, or anyone else, that I was vowing to do it, I did decide it would be something I would do.
Due to a time constraints having a child at home, I have found that some weeks, although I do try, I am not always able to complete the full 10 Perakim.
If I can’t finish them, I always try to say SOME, even if only one, and then finish throughout the week. Recently, I’ve had a hard time even finding time during the week, and had to carry over into the following week.
While I am still committed to saying them, I have found I am not necessarily able to say all 10 as I had originally decided to do.
Am I required to be Matir Neder since I haven’t kept to my original plan of saying all 10 on Shabbat? Again, I don’t believe I explicitly made a neder to do so, but I also don’t know that I was careful to say Bli Neder.
If you did say the 10 perakim the first week, then it would be considered a neder, even if you didn’t say it specifically, since you did it once with the intention of continuing it. If you didn’t say with your mouth that you were going to do this then b’dieved you can rely on the fact that you were by kol nidrei, (and said once along with the chazan), that you mean to nullify your future nedarim. We don’t rely on this for a neder that was spoken out, but if you didn’t speak it out, you can rely on it. Although the best thing would be to do hataras nidarim. It is good to get into the habit that whenever you want to do something good, to always say “bli neder”, in order to avoid such questions in the future.
Rema Y:D 211-1, Salmas Chaim Y:D 62, Minchas Shlomo 1-91(20), Kol Nidrei 73-8. As a side point, if your husband doesn’t know about your neder, according to some poskim, he can nullify the neder (be “mafir” the neder, by saying three times, “the neder is mufar” or “botil” or “void”) on the day that he hears that you made it. See Shulchan Aruch Y:D 334-37, Chavos Yair 181, Tiferes Yackov Gittin 35b, Kol Nidrei 38-13, 39- 16, and conversation with R’ Shtesman shlit”a, author of sefer Kol Nidrei.