Hadith: Do not say: What Allah wills and what so-and-so wills; rather say: What Allah wills then what so-and-so wills

عَنْ حُذَيْفَةَ رضي الله عنه أَنَّ رَسُولَ اللهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ قَالَ:
«لَا تَقُولُوا: مَا شَاءَ اللهُ وَشَاءَ فُلَانٌ، وَلَكِنْ قُولُوا: مَا شَاءَ اللهُ ثُمَّ شَاءَ فُلَانٌ».
[صحيح بمجموع طرقه] - [رواه أبو داود والنسائي في الكبرى وأحمد] - [السنن الكبرى للنسائي: 10755]

Hudhayfah (may Allah be pleased with him) reported that the Messenger of Allah (may Allah's peace and blessings be upon him) said:
"Do not say: What Allah wills and what so-and-so wills; rather say: What Allah wills then what so-and-so wills."
[Authentic by overall chains of narrators] - [Narrated by Abu Daoud & Ahmad & An-Nasa'i in Major Sunan] - [Major Sunan of An-Nasa'i - 10755]

Explanation

The Prophet (may Allah's peace and blessings be upon him) forbids Muslims from saying: "What Allah wills and what so-and-so wills" in their speech, or saying: "What Allah wills and so-and-so". This is because Allah's will and determination are absolute and none shares them with Him. but using the conjunctive "and" denotes associating someone with Allah and regarding them as equals. However, one should say: What Allah wills, then what so-and-so wills; thus, making the slave's will subordinate to Allah's will by saying "then" instead of "and", since "then" denotes sequence with a gap in time between the two things in sequence.