From "Manual of Muad'Dib" by the Princess Irulan

Come up, you lovely monster , he thought. Up. You hear me calling. Come up. Come up .
The wave lifted his feet. Surface dust swept across him. He steadied himself, his world dominated by the passage of that sand-clouded curving wall, that segmented cliff, the ring lines sharply defined in it.
Paul lifted his hooks, sighted along them, leaned in. He felt them bite and pull. He leaped upward, planting his feet against that wall, leaning out against the clinging barbs. This was the true instant of the testing: if he had planted the hooks correctly at the leading edge of a ring segment, opening the segment, the worm would not roll down and crush him.
The worm slowed. It glided across the thumper, silencing it. Slowly, it began to roll—up, up—bringing those irritant barbs as high as possible, away from the sand that threatened the soft inner lapping of its ring segment.
Paul found himself riding upright atop the worm. He felt exultant, like an emperor surveying his world. He suppressed a sudden urge to cavort there, to turn the worm, to show off his mastery of this creature.
Suddenly he understood why Stilgar had warned him once about brash young men who danced and played with these monsters, doing handstands on their backs, removing both hooks and replanting them before the worm could spill them.
Leaving one hook in place, Paul released the other and planted it lower down the side. When the second hook was firm and tested, he brought down the first one, thus worked his way down the side. The maker rolled, and as it rolled, it turned, coming around the sweep of flour sand where the others waited.
Paul saw them come up, using their hooks to climb, but avoiding the sensitive ring edges until they were on top. They rode at last in a triple line behind him, steadied against their hooks.
Stilgar moved up through the ranks, checked the positioning of Paul's hooks, glanced up at Paul's smiling face.
"You did it, eh?" Stilgar asked, raising his voice above the hiss of their passage. "That's what you think? You did it?" He straightened. "Now I tell you that was a very sloppy job. We have twelve-year-olds who do better. There was drumsand to your left where you waited. You could not retreat there if the worm turned that way."
The smile slipped from Paul's face. "I saw the drumsand."
"Then why did you not signal for one of us to take up position secondary to you? It was a thing you could do even in the test."
Paul swallowed, faced into the wind of their passage.
"You think it bad of me to say this now," Stilgar said. "It is my duty. I think of your worth to the troop. If you had stumbled into that drumsand, the maker would've turned toward you."
In spite of a surge of anger, Paul knew that Stilgar spoke the truth. It took a long minute and the full effort of the training he had received from his mother for Paul to recapture a feeling of calm. "I apologize," he said. "It will not happen again."
"In a tight position, always leave yourself a secondary, someone to take the maker if you cannot," Stilgar said. "Remember that we work together. That way, we're certain. We work together, eh?"
He slapped Paul's shoulder.
"We work together," Paul agreed.
"Now," Stilgar said, and his voice was harsh, "show me you know how to handle a maker. Which side are we on?"
Paul glanced down at the scaled ring surface on which they stood, noted the character and size of the scales, the way they grew larger off to his right, smaller to his left. Every worm, he knew, moved characteristically with one side up more frequently. As it grew older, the characteristic up-side became an almost constant thing. Bottom scales grew larger, heavier, smoother. Top scales could be told by size alone on a big worm.
Shifting his hooks, Paul moved to the left. He motioned flankers down to open segments along the side and keep the worm on a straight course as it rolled. When he had it turned, he motioned two steersmen out of the line and into positions ahead.
"Ach, haiiiii-yoh!" he shouted in the traditional call. The left-side steersman opened a ring segment there.
In a majestic circle, the maker turned to protect its opened segment. Full around it came and when it was headed back to the south, Paul shouted: "Geyrat!"
The steersman released his hook. The maker lined out in a straight course.
Stilgar said. "Very good, Paul Muad'Dib. With plenty of practice, you may yet become a sandrider."
Paul frowned, thinking: Was I not first up?
From behind him there came sudden laughter. The troop began chanting, flinging his name against the sky.
"Muad'Dib! Muad'Dib! Muad'Dib! Muad'Dib!"
And far to the rear along the worm's surface, Paul heard the beat of the goaders pounding the tail segments. The worm began picking up speed. Their robes flapped in the wind. The abrasive sound of their passage increased.
Paul looked back through the troop, found Chani's face among them. He looked at her as he spoke to Stilgar. "Then I am a sandrider, Stil?"
"Hal yawm! You are a sandrider this day."
"Then I may choose our destination?"
"That's the way of it."
"And I am a Fremen born this day here in the Habbanya erg. I have had no life before this day. I was as a child until this day."
"Not quite a child," Stilgar said. He fastened a corner of his hood where the wind was whipping it.
"But there was a cork sealing off my world, and that cork has been pulled."
"There is no cork."
"I would go south, Stilgar—twenty thumpers. I would see this land we make, this land that I've only seen through the eyes of others."