Baha’u’llah’s covenant God “didst establish…with every one who hath been created in the kingdoms of earth and heaven and in the realms of revelation and of creation."

I testify, O my God, that this is the Day whereon Thy testimony hath been fulfilled, and Thy clear tokens have been manifested, and Thine utterances have been revealed, and Thy signs have been demonstrated, and the radiance of Thy countenance hath been diffused, and Thy proof hath been perfected, and Thine ascendancy hath been established, and Thy mercy hath overflowed, and the Day-Star of Thy grace hath shone forth with such brilliance that Thou didst manifest Him Who is the Revealer of Thyself and the Treasury of Thy wisdom and the Dawning-Place of Thy majesty and power. Thou didst establish His covenant with every one who hath been created in the kingdoms of earth and heaven and in the realms of revelation and of creation. 

- Baha’u’llah  (‘Prayers and Meditations by Baha’u’llah’)

"O Son of Spirit! Turn thy face so that thou mayest find Me within thee. Powerful, Mighty and Supreme."

Thou hast asked about the statement in the Hidden Words, which reads: "O Son of Spirit! Turn thy face so that thou mayest find Me within thee. Powerful, Mighty and Supreme." This is the statement to which His Holiness the Christ, referred His apostles in the Gospel, saying. "The Father is in the Son, and the Son is in you."

This is evident that, when the hearts are purified and through divine education and heavenly teachings become the manifestors of infinite perfections, they are like clear mirrors, and the Sun of Truth will reflect with might, power and omnipotence in such a mirror, and to such an extent that whatever is brought before it is illumined and ignited. This is a brief interpretation because of the lack of time. Therefore, do thou reflect and ponder over it so that the doors of significance may be opened before thine eyes. 

- 'Abdu'l-Bahá  (From a Tablet; Star of the West, vol. 2, nos. 7 & 8, August 1, 1911)

To “ponder over these calamities and wistfully accept them, then undertake to spread the fragrances of God and exalt His Word”

…in the way of exalting the Word of God there are tests and trials, and in His love there are at all times calamities and afflictions and sufferings. Therefore, it behooveth one to first ponder over these calamities and wistfully accept them, then undertake to spread the fragrances of God and exalt His Word. At that time, whatever may befall him in the love of God, of reproach, persecution, reviling, abuse, insult, beating, imprisonment or assassination, will not offend him; rather it will augment his attraction to the Beauty of God. 

- ‘Abdu’l-Baha  (‘Tablets of ‘Abdu’l-Baha, vol. 2)

Bahá’u’lláh “offered" His son, Mirza Mihdi, “as a sacrifice” to God

Lauded be Thy name, O Lord my God! Thou seest me in this day shut up in my prison, and fallen into the hands of Thine adversaries, and beholdest my son (The Purest Branch) lying on the dust before Thy face. He is Thy servant, O my Lord, whom Thou hast caused to be related to Him Who is the Manifestation of Thyself and the Day-Spring of Thy Cause.

At his birth he was afflicted through his separation from Thee, according to what had been ordained for him through Thine irrevocable decree. And when he had quaffed the cup of reunion with Thee, he was cast into prison for having believed in Thee and in Thy signs. He continued to serve Thy Beauty until he entered into this Most Great Prison. Thereupon I offered him up, O my God, as a sacrifice in Thy path. Thou well knowest what they who love Thee have endured through this trial that hath caused the kindreds of the earth to wail, and beyond them the Concourse on high to lament.

I beseech Thee, O my Lord, by him and by his exile and his imprisonment, to send down upon such as loved him what will quiet their hearts and bless their works. Potent art Thou to do as Thou willest. No God is there but Thee, the Almighty, the Most Powerful. 

- Baha’u’llah  (‘Prayers and Meditations by Baha’u’llah’)

“Ponder in your hearts that which He hath foretold in His Tablet of the Divine Vision”

Ponder in your hearts that which He [Bahá’u’lláh] hath foretold in His Tablet of the Divine Vision that hath been spread throughout the world. Therein He saith: ‘Thereupon she wailed and exclaimed: “May the world and all that is therein be a ransom for Thy woes. O Sovereign of heaven and earth! Wherefore hast Thou left Thyself in the hands of the dwellers of this prison-city of Akká? Hasten Thou to other dominions, to Thy retreats above, whereon the eyes of the people of names have never fallen.” We smiled and spake not. Reflect upon these most exalted words, and comprehend the purpose of this hidden and sacred mystery.’ 

- ‘Abdu’l-Baha  (‘Selections from the Writings of ‘Abdu’l-Baha)