Surah Adh-Dhariyat: (20) And in the earth there are signs...

This verse is subject to two interpretations:

1. Connection to the Promise of Resurrection: It relates to the preceding statement: {Indeed, what you are promised is true. And indeed, the judgment will occur.} (51:4-5). The signs in the earth guide them to the reality that the gathering (resurrection) will happen, just as Allah says: {And among His signs is that you see the earth still, then when We send down rain upon it, it quivers and grows...} (Fussilat: 39).

2. Connection to the Actions of the Pious (Muttaqin): It relates to the deeds of the pious. Because they feared Allah and glorified Him, they showed compassion to His servants. They have signs in the earth and within themselves that confirm they have grasped the truth. Whoever observes the wondrous signs in the earth possesses complete power, thus deserving to be feared and obeyed. Whoever possesses profound wisdom and abundant blessings among the people deserves to be worshipped, and one should abandon sleep (heedlessness) for His worship. When a servant compares worship to the blessings received, he finds his gratitude insufficient and seeks forgiveness for his shortcomings. When he knows that sustenance comes from the sky, he does not withhold his wealth.

Under this second interpretation, the three subsequent verses serve to affirm what was previously stated. Therefore, the subsequent oath, {So by the Lord of the heaven and the earth} (51:23), becomes a stronger and clearer return to the discourse after the initial interjection.

There are several related issues:

Allah says elsewhere: {And a sign for them is the dead earth; We give it life...} (Ya-Sin: 33).

We have previously mentioned that the oath (the swearing by the Lord of heaven and earth) is the final recourse of the arguer. First, the proof (the signs) is presented. If the opponent does not accept it, they are accused of stubborn persistence in falsehood. If the opponent cannot refute the proof but still refuses to accept it, the arguer resorts to the oath, attributing the truth to their own sincerity.

Here, the signs of the earth did not benefit them (the disbelievers). Since the oath in {By those that scatter forth scattering} (51:1) already indicated the prior presentation of clear proofs and signs that were ineffective, the verse states: {And in the earth there are signs for those who are certain}. Even if the obstinate person gains no benefit from them, this is the case. However, in Surah Ya-Sin and other places where the signs of the earth are mentioned for the general populace, the oath was not used beforehand, so it is permissible to say that the earth contains signs for everyone who looks at it.

The Second Answer (and the more correct one): The signs here are actual signs requiring contemplation and reflection specifically for the believers. That is, these signs are realized for them. Where the text says "for them," it means there are signs if they look and reflect.

When the sign is specified for "those who are certain" (al-muqinin), the plural form is used because the certain person never neglects Allah in any state and sees signs in everything. As for the heedless person, they are only alerted by many things, so all of them collectively function as a single sign for him.