Saitama uses the spatial ring.

"Master, can you now sense a wisp of energy in your body?" Bob carefully inquired.

"Yep." Saitama feels weird finally sensing energy in his body, the scroll said that one can only sense a single wisp of energy to those who just learned it and that wisp of energy will eventaully quantified exponentially as ones cultivation progresses. Yet, Saitama wondered why instead of a single wisp of energy, he felt like all of his blood flowing out throughout his body. Saitama just brushed it as nothing though, he didn't mind it too much since he only has a level 1 talent in cultivating and wont commit much into it.

"Get this Spatial Ring of mine Master, usually this kind of level of Spatial Ring requires a high level cultivation for it to be bounded into one's own. But don't worry, I've modified it so that anyone can use it as long as one has a wisp of energy inside his body, which you have currently have." Bon presented an azure colored spatial ring. He placed it on Saitama's palm and started to ghide him.

"Now feel that wisp of energy in your body, guide it towards the ring in your hand. As long as your energy makes a contact with it, it will bind into you as I've already modified it. Imagine that wisp of energy, find the location of it first in your body, then imagine it starting from that location to flow towards the ring in your palm, guide it carefully." Bob delicately taught Saitama on how to manipulate and control the energy in his body.

"Hmm." Saitama nodded and followed what Bob instructed, but then was confused. He cannot feel a single wisp of energy in his body but instead felt his blood coursing throughout. Saitama thought that he failed as he cannot find the single strand of energy at all.

"I can't find it, I sense something flowing in my body but it is not a wisp as you said." Saitama muttered with his brows furrowed.

Bob immediately came in aid.

"How about letting me control your energy master? Don't worry, i will never dare harm you. Ill just help you to bind this ring." Bob showed his good intentions.

Letting someone's energy and senses into one's own body is a taboo. By being exposed other's energy inside ones body is like letting that person control everything of your insides. It's like putting one's life into that person's palm, if the person has malicious intentions then even if one is stronger, one can get killed immediately. Although it is extremely dangerous, Bob still want to help his Master and besides he would never ever dare to harm his Master. Even just a single punch of his master already crippled the arms of his disiciple moreso majority of the force was absorbed by the divine sword. One can only dread what would happen if he will meet up his Master punch head on.

Speaking of divine sword, his Master currently has one of them. He will ask for it later on.

"OK." Saitama answered with a poker face.

Bob slowly placed his hand in Saitama's chest, where the soul resides, and also where the energy stored. As he sent his energy in an attempt to guide Saitama's wisp of energy to help him, his ever powerful energy was blocked due to an enormous power residing inside of Saitama. With the rebound so powerful, he coughed a huge amount of blood and suffered serious internal injuries.

Bob was shocked of what happened but then soon realized why it was so.

He discovered that Saitama doesnt have any wisp of energy at all but instead a boundless and tremendously powerful energy flowing within Saitama's body. It felt like his energy was limitless, inexhaustible no matter what. Although the energy inside was boundless it was also eerily calm, as if it was a coiling dragon waiting to be disturbed.

His Master, Saitama, with a very low talent in cultivation actually have such boundless amount of universal energy same as his!. But all of it was still useless if his Master still doesn't know on how to control the energies. Its full powet will only show eventually when Saitama's cultivation rises.

Bob felt that his Master energy is the same as his, boundless, inexhaustible and overwhelmingly powerful yet also calm.

That is why Tatsumaki, the greatest esper of all time, can only lift Saitama few centimeters above ground before her head starting to spurt out some blood due to the overusage of her power, though she was also injured at that time. (Spoiler)

The reason why the rebound was so powerful was due to him being careless, sending only little of energy resulting in him being off guard by Saitama's rejection.

After the incident, Bob sat in a meditating position, circulating all of his energy throughout his body and especially the places of the injuries. After a moment, those seemingly fatal injuries was now nowhere to be seen. As if the incident never happened at all.

Saitama just looked at him as if he was a clown. His disciple just touched his chest (Saitama dont swing like that by the way), which is weird enough, but even became weirder when his disciple just coughed out blood suddenly.

"Master, to think you have such boundless energy within you. Amazing." Bob said in amazement.

"Hehe is that so." Saitama was embarassed with the praise.

"The reason why you don't feel any wisp of energy with in you was because you already have such boundless energy flowing in your body. If that is so then just imagine that feeling of energy flowing towards your palm, then imagine it letting it out for the ring to absorb." Bob said.

Saitama nodded and did what he was told.

As he looked at his palm, he can see a faint white fog covering the ring, then the ring absorb the fog. Saitama concluded it to be his energy.

"It is done Master. Now you can wear the ring." Bob said.

Saitama grabbed the ring and placed it on his ring finger in his left hand.

"What now?" Saitama inquired.

Bob waved his hand and telepathically grabbed a rock and gave it to Saitama.

"Now just think in your head to put this rock in the ring."

With a thought, Saitama saw the rock in his palm magically disappeared.

"ooh" Saitama muttered in amazement.

"And to summon it out, just think of it again. "

Again with a though, the rock appeared in his palm.

"OOH" Saitama was now satisfied.