We “should speak in the language of heaven – in the language of the spirit” – ‘Abdu’l-Baha explains

‘Abdu'l-Baha said we should speak in the language of heaven -- in the language of the spirit -- for there is a language of the spirit and heart. It is as different from our language as our own language is different from that of the animals, who express themselves only by cries and sounds.

When we pray to God a feeling fills our hearts. This is the language of the spirit which speaks to God.

When in prayer we are freed from all outward things and turn to God, then it is as if in our hearts we heard the voice of God. Without words we speak, we communicate, we converse with God and hear the answer. It is said that Moses in the wilderness heard the voice of God. But that wilderness, that holy land was his own heart. All of us when we attain to a true spiritual condition can hear the voice of God speaking to us in that wilderness. We must strive to attain to that condition by being separated from all things and from the people of the world and by turning to God alone. It will take some effort on the part of man to attain to that condition but he must work for it, strive for it. We can attain to it by thinking and caring less for material things and more for the spiritual. The further we go from the one, the nearer we are to the other the choice is ours! 

- 'Abdu'l-Baha  (Words of ‘Abdul-Baha; extract from a talk given to Laura Barney; Star of the West, vol. 8, no. 4, May 17, 1917)