The term is also related to another Arabic term, Mā šāʾ Allāh (ما شاء الله), which means "God has willed it".
This word is often used to indicate a desire to do something that you wish may occur. This also provides God's blessing on what you are about to do. For example, if you want to do something, in particular if you know that it is very hard to achieve, you invoke God's blessing before it occurs or before you set out to do it. In Judaism, B'ezrat Hashem (בעזרת השם), "With God's Help," and Im Yirtze Hashem (אם ירצה השם), "If God wishes it," are used for the same reason.
Usage of Insha'Allah derives from Islamic scripture, Surat Al Kahf (18):24 : "And never say of anything, 'I shall do such and such thing tomorrow. Except (with the saying): 'If God wills!' And remember your lord when you forget..."
Muslim scholar Ibn Abbas stated that it is in fact obligatory for a Muslim to say Insha'Allah when referring to something he or she intends to do in the future. If carelessness leads to the omission of the phrase, it may be said at a later time upon the realization of the omission.
The Spanish word ojalá and the Portuguese word oxalá (both meaning "I hope [that]") are derived from , a similar phrase meaning "if God willed it" or "if God wished it". is used for the execution of real actions (I'm going to the store if God wills it); is used to express a wish or desire one cannot fulfill (If God wished [Ojalá] that I could go to the store, but I'm busy). They are an example of the many words borrowed from Arabic due to the Muslim rule of the Iberian Peninsula from the eighth to fifteenth centuries.