أَرْضٌ earth in Arabic

كل ليلة ينزل سبعون ألف ملك من السماء إلى الأرض إلى مسجد بيت المقدس

Every night, seventy thousand angels descend from the sky to the earth, to the mosque of Bayt al-Maqdis.

الأَرْضِ the earth

al- = 'the'; ard means 'earth' — the noun after 'ila'.

From Angels at al-Aqsa

فسأل عن أعلم أهل الأرض،

He asked about the most knowledgeable person on Earth.

الأَرْضِ Earth

This closes the chain — 'the people OF the earth' — in the genitive as final owner. So the man sought out the single most learned person alive. The owner-noun ends the possessive run.

From Righteous Company

ثم سأل عن أعلم أهل الأرض،

Then he asked about the most knowledgeable person on Earth.

الأَرْضِ Earth

This closes the chain — 'the people OF the earth' — in the genitive as final owner. The man again seeks the most learned soul alive. The owner-noun ends the run.

From Righteous Company

وأظهر في الأرض الفساد والجور والكذب وخالف الخلق

And spread corruption, oppression, and falsehood on earth, and contradicted creation.

الْأَرْضِ earth

This noun, earth, sits in the genitive because the preceding preposition requires it, and its 'al-' marks it definite. It names the place inside which the corruption is spread.

From False Prophets

أيها الناس، إن الله خلق السموات والأرض في ستة أشهر، ثم استوى على العرش

O people, indeed Allah created the heavens and the earth in six months, then rose over the Throne.

وَالْأَرْضَ and the earth

The 'wa-' joins this to the previous object, continuing the list of created things. As a second object of 'created' it too takes the accusative ending, matching the first. The 'al-' marks it definite.

From Justice in the Field

قال سمعت القارئ يقرأ ولقد خلقنا السموات والأرض وما بينهما في ستة أيام فظننت الأيام أشهرًا

He said: I heard the reciter reading 'And We created the heavens and the earth and all that is between them in six days,' so I thought the days were months.

وَالْأَرْضَ and

The 'wa-' joins this to the previous object, continuing the list. As a second object of 'created' it too takes the accusative ending. The 'al-' marks it definite, the known earth set beside the known heavens.

From Justice in the Field

وَيَقُولُونَ الصِّدْقُ سَيْفُ اللَّهِ فِي الْأَرْضِ

And they say, "Truthfulness is the sword of Allah on the earth."

الْأَرْضِ the earth

A noun with 'the', so a specific known earth, and it sits in the special ending that a preposition always imposes on the word right after it. Its only job here is to be the place fixed by the preceding 'in/on'. The definiteness makes it the earth as a whole, not some patch of ground.

From Truthfulness and Righteousness

تُحِبُّهُمْ بِقَاعِ الْأَرْضِ،

The corners of the earth love them.

الْأَرْضِ the earth

The al- marks this as definite, 'the earth' as the whole world, and as the owned tail of the possessive chain it takes the 'of' (genitive) ending. It completes the phrase naming whose corners do the loving.

From Vigilance Against Worldly Deception