וַיַּ֨רְא יִשְׂרָאֵ֜ל אֶת־הַיָּ֣ד הַגְּדֹלָ֗ה אֲשֶׁ֨ר עָשָׂ֤ה יְהוָה֙ בְּמִצְרַ֔יִם וַיִּֽירְא֥וּ הָעָ֖ם אֶת־יְהוָ֑ה וַיַּֽאֲמִ֙ינוּ֙ בַּֽיהוָ֔ה וּבְמֹשֶׁ֖ה עַבְדּֽוֹ׃ (פ)
Yisrael viu a grande mão que Hashem executou contra os Mitzrim, e o povo temeu a Hashem, e creram em Hashem e em Moshe, Seu servo. {פ}
Derashot HaRan
But there is a question here, for after the splitting of the Red Sea we find it written (Ibid 14:31): "And they believed in the L-rd and in Moses, His servant," the implication being that before this their belief was not perfect.