The reward of writing down “with true faith” just “one letter” of Baha’u’llah’s Writings – the Báb explains

Better is it for a person to write down but one of His verses than to transcribe the whole of the Bayan and all the books which have been written in the Dispensation of the Bayan. For everything shall be set aside except His Writings, which will endure until the following Revelation. And should anyone inscribe with true faith but one letter of that Revelation, his recompense would be greater than for inscribing all the heavenly Writings of the past and all that has been written during previous Dispensations. Likewise continue thou to ascend through one Revelation after another, knowing that thy progress in the Knowledge of God shall never come to an end, even as it can have no beginning. (The Báb, Excerpts from the Persian Bayán, ‘Selections from the Writings of the Báb)