Absolute Oneness, Unity, and Singular Unity
احدیت — وحدت — واحدیت
Ahadiyya (Absolute Oneness) is the supreme station of the Divine Being — the maqam in which there is no differentiation whatsoever, no name, no attribute, no relation. It is pure Being-in-Itself, beyond all description. In this station, even the Name 'Allah' is not yet articulated, for that Name implies a relationship (Divinity implies worshippers). Ahadiyya is beyond all relativity.
Wahdat (Unity) is the level at which the Divine Self, so to speak, 'becomes aware' of Its own infinite potentialities — the possibility of all names, attributes, and created things. This is the level of the 'Hidden Treasure' referenced in the famous hadith qudsi: 'I was a Hidden Treasure and desired to be known, so I created the creation.' At this level, the Divine Self sees all things in a unified, undifferentiated knowledge.
كُنتُ كَنزاً مَخفِيّاً فَأَحبَبتُ أَن أُعرَفَ فَخَلَقتُ الخَلقَ
"I was a Hidden Treasure and desired to be known, so I created the creation." (Hadith Qudsi — widely cited by Sufi masters, including Ibn 'Arabi)
Wahidiyya (Singular Unity) is the level of the Divine Names and Attributes in their differentiation and multiplicity — the Divine Names such as al-'Alim (the All-Knowing), al-Qadir (the All-Powerful), al-Hayy (the Ever-Living), and so on. It is at this level that the Muhammadan Reality (Haqiqat Muhammadiyya) first appears, as the comprehensive archetype through which all other beings are manifest.