[This post was revised March 12 and 15, 2020]
There are at least six examples in the Odes of OC *-it-s rhyming with *-ut-s (whether original OC *-ut-s, or *-ut-s from OC *-up-s). This happens only when *-it-s is preceded by a labial consonant. Most likely, a dialectal sound change has taken place, changing *-it-s to *-ut-s after a [+labial] consonant, and allowing words pronounced as *-it-s elsewhere to rhyme with *-ut-s:
*-it-s > *-ut-s /[+labial] __
The locations in the Odes where this rhyming can be seen are:
- 58.5 寐 *mi[t]-s with 遂 *sə-lu[t]-s,
- 60.1 悸 *[g]ʷi[t]-s with 遂 *sə-lu[t]-s,
- 65.2 穟 *s.[ɢ]ʷi[t]-s with 醉 *Cə.tsu[t]-s [added March 15]
- 241.3 季 *kʷi[t]-s with 對 *[t]ˤ[u]p-s,
- 241.4 季 *kʷi[t]-s with 類 *[r]u[t]-s,
- 256.4 寐 *mi[t]-s with 內 *nˤ[u]p-s.
Presumably each of the twelve words above ended in [uts] in the pronunciation these odes were composed in, whence the particular rhyming pattern. Note that 季 rhymes twice with *-ut-s in different stanzas of ode 241, each time with different words: this shows the phenomenon is not a fluke, but a dialectal characteristic.
This rhyming tends to make the OC vowel in 對 *[t]ˤ[u]p-s and 內 *nˤ[u]p-s more secure, as the alternative to *u in both cases is *ə, not *i. The brackets around [u] are no more needed.
Odes 241 and 256 are part of the Da Ya, a section believed to be associated with western Zhou and (north-)western China at the time. Odes 58, 60 and 65 are from the Guo Feng section (58 and 60 from 衛風, Hebei-Henan boundary; 65 from 王風 , We may be dealing with a northern/northwestern isogloss.
For the numbering of the Odes readers should refer to Appendix B in Baxter (1992), and to Mattis List’s Shijing Rhyme Browser (March 12, 2020: thanks, Mattis, for modifying your browser to allow queries by OC rhyme! reader, to get the browser to list all Shi Jing occurrences of a certain OC rhyme, type the rhyme in B&S system, within double angle brackets, like this: «ək», in the query window).
A counterexample ?
There is in the entire Da Ya and Wei (衛) Feng sections of the Shi Jing a single example of *-it-s after a labial NOT rhyming as *-ut-s: in 245.4 (Daya), 穟 ‘ear of grain’, OC *s.[ɢ]ʷi[t]-s (same word as 穗, the older graph) rhymes with 旆, MC bajH. This MC form could go back to either of *-at-s or (following a labial consonant) *-ots , but the fact that the phonetic series’s head-word is 巿 *put ‘knee covers’ suggests that the MC reading with -ajH is anomalous, even if from *-ot-s, and that Ode 245 read 旆 as *-ut-s.
Consequently there is no strong counterexample to the change *-it-s > *-ut-s /[+labial] __ in the Da Ya, Wei (衛) Feng and Wang (王) Feng sections of the Odes, and we may regard this as a constant dialect feature of these sections of the Shi Jing.
Outside of the Daya, Wei (衛) and Wang (王) Feng, the change does not occur at all. In the Guo Feng we have:
- 30.3 寐 *mi[t]-s with 嚏 *[t]ˤi[t]-s,
- 53.1 畀 *pi[t]-s with 四 *s.li[j]-s,
- 110.2 寐 *mi[t]-s and 季 *kʷi[t]-s with 棄 *[kʰ]i[t]-s.
Odes 30, 53 and 110 belong, respectively, to Bei Feng 邶風 (Henan, between Zhengzhou and Anyang), Yong Feng 鄘風 (Henan, near Bei) and Wei Feng 魏風 (south Shanxi): a region on the middle course of the Yellow River valley.
In the Xiaoya there are no examples of the change, at all. Where *-it-s occurs after a labial consonant, it rhymes with *i words:
197.4 嘒 *qʷʰˤi[t] -s and 淠 *pʰˤi[t]-s and 寐*mi[t]-s with 屆 *kˤr[i][t]-s,
222.2 嘒 qʷʰˤi[t] -s and 淠 *pʰˤi[t]-s with 駟 *s.li[j]-s and 屆 *kˤr[i][t]-s.
In these two instances, the presence of 屆 kˤr[i][t]-s and 駟 *s.li[j]-s in the rhyme sequences guarantees that 嘒* qʷʰˤi[t] -s, 淠 *pʰˤi[t]-s and 寐*mi[t]-s were pronounced with *i vowel.
[added Feb. 14, 2021: find a sequel to this post here]