ציטירנדיקער פּירוש אויף מלכים א 17:15

שבת שבתון היא, “it is a Sabbath of solemn rest;” the word היא, here is spelled with the letter י, not as frequently elsewhere with the letter ו. On the other hand, the same word in the same context in Parshat Emor, (Leviticus 23,32) is spelled with that letter ו. Both words are read in accordance with the way they are spelled. If we want to remember this easily we can try and remember Kings I 17,15: ותאכל הוא והיא, “he and she ate;”