(The All Watchful)
The Watcher, The Observer.
Allah is Ar-Raqib (in Arabic ٱلْرَّقِيبُ), meaning the one who sees what's hidden. He is the vigilant witness and acts as a guardian protecting His creation. It also relates to the attribute of knowledge. He is the one who sees the truth in everything. He knows the secrets of every soul, and on the day of recompense, Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ will reward it for what it's earned.
From the root ra-qaf-ba (ر ق ب), which has the following classical Arabic connotations: to look, watch, be vigilant to expect, anticipate, await. To keep an eye on, detect, observe to be mindful of. To be a spy, scout, observer to regard, hold in consideration, and respect.
There are two connotations as to what it means for Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ to be the all-watchful. The first is obvious, He sees the deeds of all His servants. Nothing is hidden from His sight. Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ is well-aware of the details of every matter. Armed with this knowledge, we should be aware of ourselves, our actions, and our motives. It should inspire us to do what's right in all instances. To work diligently serving Allah's cause and seeking His approval. A constant reminder of Allah's ever-watchful nature. Living with this name at the forefront of our minds should make it easier to mitigate the evil temptations of shaitan and our ego - the two biggest enemies we face. However, this definition is just one of two and more befitting of the name Ash-Shaheed, meaning "The Observing Witness."
Yaaa aiyuhan naasut taqoo Rabbakumul lazee khalaqakum min nafsinw waahidatinw wa khalaqa minhaa zawjahaa wa bas sa minhumaa rijaalan kaseeranw wa nisaaa’aa; wattaqul laahallazee tasaaa ‘aloona bihee wal arhaam; innal laaha kaana ‘alaikum Raqeeba
"O mankind, fear your Lord, who created you from one soul and created from it its mate and dispersed from both of them many men and women. And fear Allah, through whom you ask one another, and the wombs. Indeed Allah is ever, over you, an Observer." — (Qur'an 4:1)
A neglected meaning:
A more accurate description of Ar-Raqib refers to his nature of being "watchful," not in the sense of scrutiny or judgment but just as a parent or guardian would be watchful over their child with love and care. He has not created us aimlessly to wander and become preoccupied elsewhere. Imam al-Ghazali says of Ar-Raqeeb, "is one who knows and protects." If we were aware of the constant surveillance or permanence of His gaze, we should feel safe and secure. But also, like a parent watching over a child, we should be very cautious to avoid approaching things that have been forbidden.
The Castle of Al-Marqab:
In Northern Syria, there is a castle called "Qalaat al-Marqab," which translates to "Castle of the Watchtower." This castle was strategically built 1,180 ft above sea level to overlook the Mediterranean Sea. The word Marqab shares the same Arabic root, r-q-b. A Marqab refers to something tall, high above, and looked down upon. In this case, the castle is a high vantage point to protect from potential intruders or attacks.
Maa qultu lahum illaa maaa amartanee bihee ani’budul laaha Rabbeee wa Rabbakum; wa kuntu alaihim shaheedam maa dumtu feehim falammaa tawaffaitanee kunta Antar Raqeeba alaihim; wa Anta ‘alaa kulli shai’in Shaheed
"Never did I say to them aught except what You (Allah) did command me to say: ‘Worship Allah, my Lord and your Lord.’ And I was a witness over them while I dwelt amongst them, but when You took me up, You were the Watcher over them, and You are a Witness to all things." — (Qur'an 5:117)
The lesson from Prophet Isa (as):
In this verse above, Jesus or Isa (as) describes how he was a witness to the people while he was among them. But when he was brought up from Earth to Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ there was no one to watch over His flock except Allah. Analogous to a shepherd, Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ provides food, drink, and shelter. He is the one who protects us from the harm of many dangers we're not even aware of. In the next verse, "If You should punish them – indeed they are Your servants; but if You forgive them – indeed it is You who is the Exalted in Might, the Wise." (Qur'an 5:118) Sometimes sheep will go astray, but Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ provides the signs to be guided back to the straight path. He has all the power and every right to punish, He is the shepherd or master, and we are the sheep, yet Isa (as) says, "but if You forgive them – indeed it is You who is the Exalted in Might, the Wise." Our misbehaving does not affect Him as He is "Exalted in Might." His forgiveness is not a sign of weakness but a mark of His intelligence, wisdom, and kindness.
In one hadith, it describes how the companions gathered around the Prophet ﷺ and asked questions about Al-Imaan, Al-Islam, and Al-Ihsan. In the hadith, they discussed the obligations of Al-Imaan and affirmed Al-Qadr (the divine decree of Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ). It is quite a long hadith, but at one point, it was asked of Prophet ﷺ "Inform me about al-Ihsan (perfection or performance of good deeds). He ﷺ said: That you worship Allah as if you are seeing Him, for though you don't see Him, He, verily, sees you. 
A common thread that runs through each name requires us to look inward. The believer benefits from this self-monitoring, not just from doing immoral acts but asking if they are living up to their potential. Are they using their time in a manner that Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ would be pleased to see? By truly embracing this perspective, a person can become more aware of how they dispense with their time. A person looks to see how they can be more productive and contribute to the well-being of their community, family, or friends. However, we must learn to balance, to not live with guilt to take time to enjoy the many blessings Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ has provided for us as well. In Surah Ar-Rahman verse 13, "So which of the favors of your Lord would you deny?"
Imam al-Ghazali also warns, "knowing that his own soul is an enemy to him, and that Satan is his enemy; and that both of them take the opportunity to prompt him to forgetfulness and disobedience." This is similar to the famous African proverb, "if there is no enemy within, the enemy outside can do us no harm." Suppose we learn to understand the root of our desires, fears, and insecurities. In that case, we can neutralize the destructive ways they manifest. If we are watchful over ourselves, we can protect ourselves from many shortcomings.
 Sahih Muslim 8a & Sahih al-Bukhari 50