A Jewish man came to the Prophet ﷺ and said, "You set up rivals to Allah and you commit shirk. You say, 'Whatever Allah wills and you will,' and you say, 'By the Kaabah!'"So the Prophet ﷺ instructed them, when they wished to take an oath, to say, "By the Lord of the Kaabah," and to say, "Whatever Allah wills, then you will."
أن يهوديا أتى النبي ﷺ فقال: إنكم تنددون وإنكم تشركون تقولون: ما شاء الله وشئت! وتقولون: الكعبة! فأمرهم النبي ﷺ إذا أرادوا أن يحلفوا أن يقولوا: ورب الكعبة، ويقولوا: ما شاء الله ثم شئت.
Nasai (3773) narrated it from Yusuf bin Isa, who said, Fadl bin Musa told us, Masaar told us, from Mabad bin Khalid, from Abdullah bin Yasar, from Qutaylah, and he mentioned it. Its chain is sahih. Hafiz also declared it sahih in Isabah after attributing it to Nasai.Ahmad (27093) narrated it from Yahya bin Saeed, who said, Masudi told us, who said, Mabad bin Khalid told me, with his chain, and this is his wording, from Qutaylah bint Sayfi Juhaniyyah, who said, a rabbi from among the rabbis came to the Messenger of Allah and said, "O Muhammad, you people are excellent, were it not that you associate partners with Allah." He said, "Glory be to Allah, what is that?" He said, "You say when you swear an oath, 'By the Kaaba.'" She said, the Messenger of Allah paused for a while, then said, "He has indeed said the truth, so whoever wishes to swear an oath, let him swear by the Lord of the Kaaba." Then he said, "O Muhammad, you people are excellent, were it not that you set up a rival to Allah." He said, "Glory be to Allah, what is that?" He said, "You say, 'What Allah wills and you will.'" She said, the Messenger of Allah paused for a while, then said, "He has indeed said the truth, so whoever says, 'What Allah wills,' let him separate between the two statements, then say, 'then you will.'"Masudi's memory became confused later in life, but Yahya bin Saeed narrated from him before that confusion set in. Hakim (4/97) narrated it through another route from Masudi in abridged form, and said, its chain is sahih.As for what Abu Dawud (4980) and Imam Ahmad (23265) both narrated from the hadith of Shubah, from Mansur, from Abdullah bin Yasar, from Huzaifa, from the Prophet, in abridged form, "Do not say, 'What Allah wills and so-and-so wills,' but say, 'What Allah wills, then so-and-so wills,'" this is a broken chain, for Abdullah bin Yasar did not hear from Huzaifa, as Ibn Main stated.Uthman bin Saeed Darimi said, I asked Yahya bin Main about Abdullah bin Yasar, the one from whom Mansur narrates, from Huzaifa, "Do not say, 'What Allah wills and so-and-so wills,'" did he meet Huzaifa? He said, I do not know of it. See, Tarikh Ibn Main (567), and Alai likewise mentioned it in Jami Tahsil (407).It has already been noted that Rabi bin Harash corroborated him, from Huzaifa, but Bukhari and others preferred the view that it belongs to the musnad of Tufayl bin Sakhbara, brother of Ayesha, as mentioned earlier. Bukhari also preferred the narration of Mansur from Abdullah bin Yasar, from Huzaifa, over the narration of Mabad bin Khalid from Abdullah bin Yasar, from Qutaylah, as Tirmidhi mentioned in Ilal al-Kabir (2/659). And Allah knows best what is correct.As for his statement, "Do not say, 'What Allah wills and so-and-so wills,'" it is because this phrasing implies equating the two.