The proponents of the first view reply:

An oath may serve to affirm or deny something, as when someone says, “By Allah, it will certainly rain,” or, “It will not rain.” This is a purely declarative statement, containing neither encouragement nor restraint. Even if he swears according to his belief, he has broken his oath if matters turn out contrary to what he swore. This makes clear the distinction between swearing about the past and swearing about the future. An oath concerning the past does not become binding, so if he is mistaken, no expiation is required, just as none is required for a deliberately false oath. An oath concerning the future is different. Nor is he required to add “if Allah wills” concerning the future if he has done it.

Allah Most High says:

“Those who disbelieve claim that they will never be resurrected. Say, ‘Yes, by my Lord, you will surely be resurrected; then you will surely be informed of what you did. And that is easy for Allah.’”

Thus, He commanded him to swear about what would happen in the future. Likewise, He says:

“Those who disbelieve say, ‘The Hour will not come to us.’ Say, ‘Yes, by my Lord, it will surely come to you.’”

He also commanded him to swear about a present reality, saying:

“They ask you, ‘Is it true?’ Say, ‘Yes, by my Lord, it is indeed true.’”

The Prophet, may Allah bless him and grant him peace, said:

“By Him in whose hand is my soul, the son of Mary will surely descend among you as a just judge and an equitable leader.”

He also said:

“By Him in whose hand is my soul, this world will not pass away until a day comes upon people when neither the killer knows why he killed nor the slain why he was killed.”

And he said:

“When Chosroes perishes—or, Chosroes will surely perish—there will then be no Chosroes after him. When Caesar perishes, there will be no Caesar after him. By Him in whose hand is my soul, their treasures will surely be spent in Allah’s cause.”

Both reports are in al-Sahīh (The Authentic Collection). Thus, on many occasions, he—may Allah’s blessings and peace be upon him—swore about the future without adding “if Allah wills.”

Allah—glorified and exalted is He—knows best. All praise belongs to Allah, Lord of the worlds. May Allah bless our master Muhammad, his family, and his Companions, and grant them peace.