Is ghusl valid if it is not preceded by an explicit intention, whether verbally or in the heart?

For a mandatory or recommended ghusl (ritual bath), it is a condition to have the intention in the heart to remove janabah (state of ritual impurity) or to attain reward, and it is not a condition to utter it verbally. As for a ghusl that is neither mandatory nor recommended, no intention is required for it. Saying "Bismillah" (in the name of Allah) before ghusl is a Sunnah according to the majority of scholars and is not obligatory.