Verse, or poetry proper, was a development of rejez. As poetical culture was extended, the Arabs felt the want of more harmonious and stately measures, and gradually formed for themselves a more varied and yet a more severe versification. Throughout the Arab prosody we may, however, trace the primitive and rudimentary rejez in the iambic and anapæstic character of the lines. The taste and scholarship of Ḥarîri have enabled him to diversify his work by introducing most the metres which were in use in his time; but among the older poets only four or five of these were commonly employed. In the celebrated collection of Arab verses, called the Ḥamâseh of Abû Temmâm, more than five hundred of the pieces are in the metre ṭawîl; the kâmil, wâfir, and basîṭ follow at a great distance, each having less than a hundred, while the others are but sparingly used. Of the seven Mo‘allaḳât, as generally given, those of Imr al Ḳays, Ṭarafeh, and Zohayr ibn Abi Sulmè are of the metre ṭawîl, those of Lebîd and ‘Antarah are kâmil, that of ‘Amr ibn Kulthûm is wâfir, and that of Ḥârith ibn Ḥillizeh is khafîf. The favourite metre of the early poets, the ṭawîl, is remarkable for its grave and sonorous character—it may be called the heroic measure of the Arabs. In some verses, addressed by Abû ’l ‘Ala to a man of letters, the poet, excusing his own deficiencies, says, by way of illustration, “Do you not know that the metre which is the most complete of metres, is sometimes modified by a weak letter.” This epithet of “complete” is explained to refer to the ṭawîl, because a verse of this metre may consist of forty-eight letters, while in the medîd and basîṭ the longest verse can only contain forty-two. This property from which it takes its name, and also the prevalence of long syllables, made it especially suitable to the loftier class of poetry, whether descriptive or elegiac. The kâmil is in its structure the most closely related to the rejez. Indeed, a kâmil line may become pure rejez by the employ­ment of permissible licences, though if the peculiarity of the kâmil, the use of two short syllables at the beginning of the foot appear even once, the poem is considered to be in kâmil, and not in rejez. It would, therefore, seem that kâmil and the closely related metre wâfir represent the first developments of the rejez, and mark the transition to a more elaborate versification.

Ḥarîri, one of whose aims was to exhibit the classic metres, uses for the most part those for which there is high authority; but, long before his time, the poets of Islam had added to the number which had been known during the Ignorance. Although the metres of the old time were looked upon as the best and noblest, and justly so, since they sprang from the original poetical life of the people, yet the craving for variety, and, perhaps, the intercourse with other nations, led poets to seek new forms of versification. One of the first who did this was the celebrated Ḥabîb ibn ‘Ows, commonly known as Abû Temmâm. He was born about the year 190 (a.d. 805), near Damascus, and is placed with his country­man Mutenebbi in the first rank of the later poets. His profound knowledge of the Arabic literature is proved by the collection of poetical pieces, called the Ḥamâseh, which he made, and which is only one of three similar compila­tions; the other two being the Foḥûl ash Shu‘arâ (the Heroes of the Poets), and the Ikhtiyârât, or Selections. He is said to have known by heart fourteen thousand pieces of the metre rejez, besides Ḳaṣidehs, and fragments. Nor were his own compositions few. His poems in all the various classes of eulogy, satire, elegy, and the rest, are said to number 484, and to contain 7707 verses. Two or three new metres are ascribed to him, and as he had an unbounded popularity in his own age, it is probable that the poets who imitated him considered his authority for their use as equal to that of the ancients. But the best writers restricted themselves generally to the sixteen metres described by Khalîl ibn Aḥmed, the systematizer of the national prosody; and even of these some have always been but little used. The Persians, who adopted the Arabic versification, have formed for themselves other metres, such as ḳarîb, jedîd, and mushâkil, and have invented circles to explain the metamorphoses of the Ruba‘î, or quatrain, which they orignated. But in Ḥarîri, the forms of the original Arabic poetry will be found almost unperverted. His work resumes all that was most classical and of the highest authority in the writings of his predecessors, and no better aid to the study of the laws of Khalîl can be found than the diverse improvisations of Abû Zayd.