Allah Most High:

“Fear Allah and speak words of appropriate justice.”

They explained this as “upright and true.” Ibn ‘Abbās explained it as “correct”; Qatādah and Muqātil as “just”; and al-Suddī as “straight.” All these explanations are correct, for sound speech accords with what is right. If it conveys information, it is truthful, corresponding to what it reports without addition or omission. If it gives a command, it commands justice without excess or deficiency. Hence they explain sadād (soundness) in terms of qasd (uprightness), and qasd in terms of justice.

Al-Jawharī said:

“Tasdīd means enabling someone to attain sadād: correctness and uprightness in speech and action. A man is described as musaddad when he acts correctly and uprightly. Musaddad also means ‘straightened’; one says saddada rumhahu, ‘he straightened his spear.’ An affair described as sadīd or asadd is rightly directed. Istadda, said of something, means that it became straight.

“The poet said:

‘I teach him archery every day;
Then, when his arm aimed true, he shot at me.’

“Al-Asma‘ī said: ‘The reading ishtadda [grew strong], with the dotted sh, is of no account.’”

Their explanation of sadd (blocking) in terms of qasd shows that the word qasd carries the sense of gathering together and strength. Qasd means justice, just as it means soundness and correctness: exact correspondence and agreement, without excess or deficiency. This combines completeness with exact correspondence. From this comes the statement of Allah Most High:

“And upon Allah is the direction of the way.”

That is, the way characterized by qasd—the just way. This means that the just way leads to Him, as Allah Most High says:

“Indeed, upon Us is guidance.”

That is, guidance leads to Us.