1. He forbade the use of the sword.
2. He stated that no other Manifestations will appear before one thousand years. This was later reiterated in the Kitáb-i-Badí' and in The Kitáb-i-Aqdas.
3. He stated that, as from that moment, all the names and attributes of God were manifested within all created things, implying the advent of a new Day. [RB1:278–80]

During the 12 days in the Ridván Garden Bahá'u'lláh confided to 'Abdu'l-Bahá that He was 'Him Whom God shall make manifest'. [CH82]

The garden was located in a large agricultural area immediately north of the walls of the city of Baghdad, about 450 metres (1,480 ft) from the city's northern Mu'azzam gate. Located on the eastern bank of the Tigris River in what is now the Bab al-Mu'azzam neighbourhood of Baghdad's Rusafa District, it was directly opposite the district in which Bahá'u'lláh lived during his stay in the city, on the river's western bank. [Wikipedia]

Extract from a Tablet of Baha'u'llah-Khadimu'llah. (Edited provisional translation below)

"On the first day that the Ancient Beauty occupied the Most Great Throne in a Garden which hath been designated Ridván, the Tongue of Grandeur uttered three blessed verses.
[1] The first of them was that in this Manifestation the use of the sword in holy war is put aside.
[2] Secondly, prior to the completion of a millennium any theophanological claim put forward by any person must be considered baseless. In this respect the year should be considered a complete year.
[3] Thirdly, the True One, exalted be His Glory, at that time manifested all the Divine Names upon all things.
"Verily, all created things were immersed in the sea of purification when, on that first day of Ridván, We shed upon the whole of creation the splendours of Our most excellent Names and Our most exalted Attributes". [Kitab-i-Aqdas para75 p47]

And the following choice verse was subsequently revealed but has been ordained to be of the same rank as the preceding three; namely, whatever personal designations are mentioned before the Face, whether living or dead, such have thereby attained the Presence of God by virtue of being mentioned by the King of Pre-Existence. [UCMERCED site]