The Vast, The All-Embracing, The Boundless.
Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ is Al-Wasi (in Arabic: ٱلْوَاسِعُ): The one who’s knowledge, mercy, and provision are vast. He is of limitless capacity and abundance and gives without expecting anything in return. Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ embraces all things and His wisdom and mercy are boundless.
From the root waw-sin-ayn (و س ع), which has the following classical Arabic connotations: to be sufficient in capacity or size, wide, spacious to be ample, plentiful, bountiful, rich to comprehend, embrace, include, take in, pervade, limitless capacity, and abundance.
The name Al-Wasi has been mentioned nine times in the Qur'an and has a variety of meanings that we will uncover. The first refers to His vastness. Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ is everywhere. Wherever you may be, He is with you. His vastness encompasses the entirety of the universe. He is not limited or bounded to one geographic location. He listens and responds to all who ask of Him because of the attribute of being Al-Wasi.
Wa lillaahil mashriqu walmaghrib; fa aynamaa tuwalloo fasamma wajhullaah; innal laaha waasi’un Aleem
"And to Allah belongs the east and the west. So wherever you [might] turn, there is the Face of Allah. Indeed, Allah is all-Encompassing and Knowing." — (Qur'an 2:115)
Another aspect of this name refers to the vastness of Allah's mercy encompasses. His mercy, knowledge, and power are infinite. It is the work of shaitan to make you believe that your plea for forgiveness will be rejected. The Qur'an and hadith affirm that our Lord is merciful. We may have done terrible things in the past. We may have repeated the same mistake to the point where it seems unredeemable. But how can we deny ourselves the mercy of Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ when He says:
Ash Shaitaanu ya'idukumul faqra wa ya'murukum bilfahshaaa'i wallaahu ya'idukum maghfiratam minhu wa fadlaa; wallaahu Waasi'un 'Aleem
"Satan threatens you with poverty and orders you to immorality, while Allah promises you forgiveness from Him and bounty. And Allah is all-Encompassing and Knowing." — (Qur'an 2:268)
On the authority of Anas (may Allah be pleased with him), who said: I heard the Messenger of Allah ﷺ say: Allah the Almighty said: O son of Adam, so long as you call upon Me and ask of Me, I shall forgive you for what you have done, and I shall not mind. O son of Adam, were your sins to reach the clouds of the sky and you were then to ask forgiveness of Me, I would forgive you. O son of Adam, were you to come to Me with sins nearly as great as the earth and were you then to face Me, ascribing no partner to Me, I would bring you forgiveness nearly as great as it. It was related by at-Tirmidhi (also by Ahmad ibn Hanbal). Its chain of authorities is sound.
Qul yaa'ibaadiyal lazeena asrafoo 'alaaa anfusihim laa taqnatoo mirrahmatil laah; innal laaha yaghfiruz zunooba jamee’aa; innahoo Huwal Ghafoorur Raheem
"Say, 'O My servants who have transgressed against themselves [by sinning], do not despair of the mercy of Allah. Indeed, Allah forgives all sins. Indeed, it is He who is the Forgiving, the Merciful.'" — (Qur'an 39:53)
Al-Wasi in divorce:
Wa iny-yatafarraqaa yughnil laahu kullam min sa’atih; wa kaanal laahu Waasi’an Hakeemaa
"But if they separate [by divorce], Allah will enrich each [of them] from His abundance. And ever is Allah Encompassing and Wise." — (Qur'an 4:130)
Another connotation we can infer from this ayah is Allah is Al-Wasi, the one whose provision is all-encompassing. In extenuating circumstances, divorce happens, and when it does, Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ reassures that both parties should not fear scarcity, clawing to one-up each other. Reconciliation and protecting the sanctity of marriage should be the priority, but if that ship has presumably sailed, then seek fairness as Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ will enrich both from His abundance.
Wa laa tu'minooo illaa liman tabi'a deenakum qul innal hudaa hudal laahi ai yu'taaa ahadum misla maaa ooteetum aw yuhaaajjookum inda Rabbikum, qul innal fadla biyadil laah; yu'teehi mai yashaaa; wallaahu Waasi'un 'Aleem
"And do not trust except those who follow your religion.” Say, “Indeed, the [true] guidance is the guidance of Allah. [Do you fear] lest someone be given [knowledge] like you were given or that they would [thereby] argue with you before your Lord?” Say, “Indeed, [all] bounty is in the hand of Allah – He grants it to whom He wills. And Allah is all-Encompassing and Wise." — (Qur'an 3:73)
Among these verses where Al-Wasi is mentioned, you see the pairing of names with the all-merciful, the all-knowing, and the all-wise. This name furthers the perfection of all His attributes. They are all-encompassing and have no extent to which they can be depleted or diminished. Imam Ghazali writes, "His knowledge be considered, the sea of things He knows has no shore; in fact the seas would be exhausted if they were ink for His words."
The believer benefits from knowing Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ is Al-Wasi in that they understand their Lord loves them. His mercy extends to all and knows no boundaries. It is all-encompassing and vast. This should bring great relief to the one who turns to Him, often asking for His forgiveness. It was narrated from Aisha (ra) that she said: "Praise be to Allah Whose hearing encompasses all voices. We also must look within ourselves; we are constrained and limited in many ways. Our intellect has boundaries, and our physical body has constraints, but can we say honestly we've stretched to see what's possible? Are we living close to these limits? Probably not. We are all likely to be living well beneath the potential Allah سُبْحَٰنَهُۥ وَتَعَٰلَىٰ has made us capable of. We have a lot to offer and a lot to learn. Our connection to this name is through the expansion of our knowledge, our deen, and our character.
 Hadith #34, 40 Hadith Qudsi
 Sahih (Darussalam) Sunan an-Nasa'i 3460