The Khumus is meant for the needs of Allah‘s Messenger ﷺ and the poor

Narrated 'Ali:

Fatima complained of what she suffered from the hand mill and from grinding, when she got the news that some slave girls of the booty had been brought to Allah's Apostle. She went to him to ask for a maid-servant, but she could not find him, and told 'Aisha of her need. When the Prophet came, Aisha informed him of that. The Prophet came to our house when we had gone to our beds. (On seeing the Prophet) we were going to get up, but he said, 'Keep at your places,' I felt the coolness of the Prophet's feet on my chest. Then he said, "Shall I tell you a thing which is better than what you asked me for? When you go to your beds, say: 'Allahu Akbar (i.e. Allah is Greater)' for 34 times, and 'Alhamdu Lillah (i.e. all the praises are for Allah)' for 33 times, and Subhan Allah (i.e. Glorified be Allah) for 33 times. This is better for you than what you have requested."

حَدَّثَنَا بَدَلُ بْنُ الْمُحَبَّرِ، أَخْبَرَنَا شُعْبَةُ، قَالَ أَخْبَرَنِي الْحَكَمُ، قَالَ سَمِعْتُ ابْنَ أَبِي لَيْلَى، حَدَّثَنَا عَلِيٌّ، أَنَّ فَاطِمَةَ ـ عَلَيْهَا السَّلاَمُ ـ اشْتَكَتْ مَا تَلْقَى مِنَ الرَّحَى مِمَّا تَطْحَنُ، فَبَلَغَهَا أَنَّ رَسُولَ اللَّهِ ﷺ أُتِيَ بِسَبْىٍ، فَأَتَتْهُ تَسْأَلُهُ خَادِمًا فَلَمْ تُوَافِقْهُ، فَذَكَرَتْ لِعَائِشَةَ، فَجَاءَ النَّبِيُّ ﷺ فَذَكَرَتْ ذَلِكَ عَائِشَةُ لَهُ، فَأَتَانَا وَقَدْ دَخَلْنَا مَضَاجِعَنَا، فَذَهَبْنَا لِنَقُومَ فَقَالَ " عَلَى مَكَانِكُمَا " حَتَّى وَجَدْتُ بَرْدَ قَدَمَيْهِ عَلَى صَدْرِي فَقَالَ " أَلاَ أَدُلُّكُمَا عَلَى خَيْرٍ مِمَّا سَأَلْتُمَاهُ، إِذَا أَخَذْتُمَا مَضَاجِعَكُمَا فَكَبِّرَا اللَّهَ أَرْبَعًا وَثَلاَثِينَ، وَاحْمَدَا ثَلاَثًا وَثَلاَثِينَ، وَسَبِّحَا ثَلاَثًا وَثَلاَثِينَ، فَإِنَّ ذَلِكَ خَيْرٌ لَكُمَا مِمَّا سَأَلْتُمَاهُ ".