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

He doesn't even see the problem , Hawat thought. The naпvetй of the Fremen was frightening.
"They're concerned for a respected comrade," Hawat said.
"We will treat your comrade with the same reverence we treat our own," the Fremen said. "This is the bond of water. We know the rites. A man's flesh is his own; the water belongs to the tribe."
Hawat spoke quickly as the man with the lasgun advanced another step. "Will you now help our wounded?"
"One does not question the bond," the Fremen said. "We will do for you what a tribe does for its own. First, we must get all of you suited and see to the necessities."
The man with the lasgun hesitated.
Hawat's aide said: "Are we buying help with Arkie's . . . water?"
"Not buying," Hawat said. "We've joined these people."
"Customs differ," one of his men muttered.
Hawat began to relax.
"And they'll help us get to Arrakeen?"
"We will kill Harkonnens," the Fremen said. He grinned. "And Sardaukar." He stepped backward, cupped his hands beside his ears and tipped his head back, listening. Presently, he lowered his hands, said: "An aircraft comes. Conceal yourselves beneath the rock and remain' motionless."
At a gesture from Hawat, his men obeyed.
The Fremen took Hawat's arm, pressed him back with the others. "We will fight in the time of fighting," the man said. He reached beneath his robes, brought out a small cage, lifted a creature from it.
Hawat recognized a tiny bat. The bat turned its head and Hawat saw its blue-within-blue eyes.
The Fremen stroked the bat, soothing it, crooning to it. He bent over the animal's head, allowed a drop of saliva to fall from his tongue into the bat's upturned mouth. The bat stretched its wings, but remained on the Fremen's opened hand. The man took a tiny tube, held it beside the bat's head and chattered into the tube; then, lifting the creature high, he threw it upward.
The bat swooped away beside the cliff and was lost to sight.
The Fremen folded the cage, thrust it beneath his robe. Again, he bent his head, listening. "They quarter the high country," he said. "One wonders who they seek up there."
"It's known that we retreated in this direction," Hawat said.
"One should never presume one is the sole object of a hunt," the Fremen said. "Watch the other side of the basin. You will see a thing."
Time passed.
Some of Hawat's men stirred, whispering.
"Remain silent as frightened animals," the Fremen hissed.
Hawat discerned movement near the opposite cliff—flitting blurs of tan on tan.
"My little friend carried his message," the Fremen said. "He is a good messenger—day or night. I'll be unhappy to lose that one."
The movement across the sink faded away. On the entire four to five kilometer expanse of sand nothing remained but the growing pressure of the day's heat—blurred columns of rising air.
"Be most silent now," the Fremen whispered.
A file of plodding figures emerged from a break in the opposite cliff, headed directly across the sink. To Hawat, they appeared to be Fremen, but a curiously inept band. He counted six men making heavy going of it over the dunes.
A "thwok-thwok" of ornithopter wings sounded high to the right behind Hawat's group. The craft came over the cliff wall above them—an Atreides 'thopter with Harkonnen battle colors splashed on it. The 'thopter swooped toward the men crossing the sink.
The group there stopped on a dune crest, waved.
The 'thopter circled once over them in a tight curve, came back for a dust-shrouded landing in front of the Fremen. Five men swarmed from the 'thopter and Hawat saw the dust-repellent shimmering of shields and, in their motions, the hard competence of Sardaukar.
"Aiihh! They use their stupid shields," the Fremen beside Hawat hissed. He glanced toward the open south wall of the sink.
"They are Sardaukar," Hawat whispered.
"Good."
The Sardaukar approached the waiting group of Fremen in an enclosing half-circle. Sun glinted on blades held ready. The Fremen stood in a compact group, apparently indifferent.
Abruptly, the sand around the two groups sprouted Fremen. They were at the ornithopter, then in it. Where the two groups had met at the dune crest, a dust cloud partly obscured violent motion.
Presently, dust settled. Only Fremen remained standing.
"They left only three men in their 'thopter," the Fremen beside Hawat said. "That was fortunate. I don't believe we had to damage the craft in taking it."
Behind Hawat, one of his men whispered: "Those were Sardaukar!"
"Did you notice how well they fought?" the Fremen asked.
Hawat took a deep breath. He smelled the burned dust around him, felt the heat, the dryness. In a voice to match that dryness, he said: "Yes, they fought well, indeed."
The captured 'thopter took off with a lurching flap of wings, angled upward to the south in a steep, wing-tucked climb.