Ali and Fatimah were very poor actually. Unlike many other homes, they had no money to afford to have a servant or a maid to help out in the housework.
So Fatimah used to do everything, and you got to appreciate that because there were no washing machines, no dishwashers, no vacuums… it was all physical work.
So, Ali hearing this he says:
“O Fatimah! How about you get a servant?”
“How can I get a servant? We don’t have money?”
He tells her:
“I have heard that your father Muhammad (peace be upon him) just recently received some prisoners of war, and why not you go and request from him to give you one of those people to be a servant for us?”
Fatimah liked the idea and she heads there right away. She knocks on the door, Aisha opens the door, and they greet each other. Fatimah asks:
“O Aisha, is my father here?”
“No, he’s not here.”
Then Fatimah basically wants to tell her exactly what the request is like, and she told her:
“I heard my father’s received some prisoner of war and I was hoping I can get one to be like a servant to help me.”
“The moment your father comes back, I will surely let him know of what your need is.”
Fatimah goes back home.
The Prophet, after some time, comes back to his house, and Aisha tells him exactly why Fatimah came, and that she’s looking for a servant to help her out with all the housework.
Being an amazing father, the Prophet did not delay it for two or three days, he says:
You know what, I’m going to go right now to the house of Ali.
As he gets there, Ali and Fatimah would like to stand up and greet the Prophet, but the Prophet says:
Stay the way you are, no need to stand up.
The Prophet comes and sits in between Fatimah and Ali and said:
Shall I not guide you of something that is better and more beneficial to both of you than whatever you have requested (having a servant)? Whenever you’re about to go to sleep, say Subhanallah 33 times, say Alhamdulillah 33 times, and say Allahu Hu Akbar 34 times. This is better for you than having a servant. (Al-Bukhari) Say these remembrances (dua) before you sleep and Allah will boost you with physical energy that you’re able to work the following day; you’ll feel as if someone is supporting you, as if there’s a servant helping you. That’s how much energy you will have.
And some other understanding of this narration is that you will not feel as exhausted whenever you do the actual daily work that you’re used to because of that dua you’ve said that night before.