‘And the man Elkanah, and all his house, went up to offer unto the LORD.’ Elkanah went up annually, but the narrative tells us that Hannah didn't go up with him: not that year, nor the following year.
We must not foolishly put temptation in our way. We must know ourselves. There was nothing sinful, of course, about Hannah’s love for Samuel, and yet because she had vowed in her heart to give him to the Lord, she had to be very careful not to go back on her word. If we make a vow to God – and it is not a hasty or ill-considered vow – then we must take steps to protect it from our own weakness. A vow is likely to be something difficult for us to do, and we will not add to the difficulty by coming close to not keeping it.